content/browser/frame_host/navigation_controller

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This source file includes following definitions.
NotifyPrunedEntries
SetPageStateIfEmpty
ControllerRestoreTypeToEntryType
ConfigureEntriesForRestore
AreURLsInPageNavigation
ShouldKeepOverride
CreateNavigationEntry
DisablePromptOnRepost
GetSmoothedTime
screenshot_manager_
GetWebContents
GetBrowserContext
SetBrowserContext
Restore
Reload
ReloadIgnoringCache
ReloadOriginalRequestURL
ReloadInternal
CancelPendingReload
ContinuePendingReload
IsInitialNavigation
GetEntryWithPageID
LoadEntry
SetPendingEntry
GetActiveEntry
GetVisibleEntry
GetCurrentEntryIndex
GetLastCommittedEntry
CanViewSource
GetLastCommittedEntryIndex
GetEntryCount
GetEntryAtIndex
GetEntryAtOffset
GetIndexForOffset
TakeScreenshot
SetScreenshotManager
CanGoBack
CanGoForward
CanGoToOffset
GoBack
GoForward
GoToIndex
GoToOffset
RemoveEntryAtIndex
UpdateVirtualURLToURL
LoadURL
LoadURLWithParams
RendererDidNavigate
ClassifyNavigation
RendererDidNavigateToNewPage
RendererDidNavigateToExistingPage
RendererDidNavigateToSamePage
RendererDidNavigateInPage
RendererDidNavigateNewSubframe
RendererDidNavigateAutoSubframe
GetIndexOfEntry
IsURLInPageNavigation
CopyStateFrom
CopyStateFromAndPrune
CanPruneAllButLastCommitted
PruneAllButLastCommitted
PruneAllButLastCommittedInternal
ClearAllScreenshots
SetSessionStorageNamespace
SetMaxRestoredPageID
GetMaxRestoredPageID
GetSessionStorageNamespace
GetDefaultSessionStorageNamespace
GetSessionStorageNamespaceMap
NeedsReload
SetNeedsReload
RemoveEntryAtIndexInternal
DiscardNonCommittedEntries
GetPendingEntry
GetPendingEntryIndex
InsertOrReplaceEntry
PruneOldestEntryIfFull
NavigateToPendingEntry
NotifyNavigationEntryCommitted
max_entry_count
SetActive
LoadIfNecessary
NotifyEntryChanged
FinishRestore
DiscardNonCommittedEntriesInternal
DiscardPendingEntry
DiscardTransientEntry
GetEntryIndexWithPageID
GetTransientEntry
SetTransientEntry
InsertEntriesFrom
SetGetTimestampCallbackForTest
// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/frame_host/navigation_controller_impl.h"

#include "base/bind.h"
#include "base/debug/trace_event.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"  // Temporary
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/time/time.h"
#include "content/browser/browser_url_handler_impl.h"
#include "content/browser/dom_storage/dom_storage_context_wrapper.h"
#include "content/browser/dom_storage/session_storage_namespace_impl.h"
#include "content/browser/frame_host/debug_urls.h"
#include "content/browser/frame_host/interstitial_page_impl.h"
#include "content/browser/frame_host/navigation_entry_impl.h"
#include "content/browser/frame_host/navigation_entry_screenshot_manager.h"
#include "content/browser/renderer_host/render_view_host_impl.h"  // Temporary
#include "content/browser/site_instance_impl.h"
#include "content/common/frame_messages.h"
#include "content/common/view_messages.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/invalidate_type.h"
#include "content/public/browser/navigation_details.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/notification_types.h"
#include "content/public/browser/render_widget_host.h"
#include "content/public/browser/render_widget_host_view.h"
#include "content/public/browser/storage_partition.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/common/content_client.h"
#include "content/public/common/content_constants.h"
#include "content/public/common/url_constants.h"
#include "net/base/escape.h"
#include "net/base/mime_util.h"
#include "net/base/net_util.h"
#include "skia/ext/platform_canvas.h"

namespace content {
namespace {

const int kInvalidateAll = 0xFFFFFFFF;

// Invoked when entries have been pruned, or removed. For example, if the
// current entries are [google, digg, yahoo], with the current entry google,
// and the user types in cnet, then digg and yahoo are pruned.
void NotifyPrunedEntries(NavigationControllerImpl* nav_controller,
                         bool from_front,
                         int count) {
  PrunedDetails details;
  details.from_front = from_front;
  details.count = count;
  NotificationService::current()->Notify(
      NOTIFICATION_NAV_LIST_PRUNED,
      Source<NavigationController>(nav_controller),
      Details<PrunedDetails>(&details));
}

// Ensure the given NavigationEntry has a valid state, so that WebKit does not
// get confused if we navigate back to it.
//
// An empty state is treated as a new navigation by WebKit, which would mean
// losing the navigation entries and generating a new navigation entry after
// this one. We don't want that. To avoid this we create a valid state which
// WebKit will not treat as a new navigation.
void SetPageStateIfEmpty(NavigationEntryImpl* entry) {
  if (!entry->GetPageState().IsValid())
    entry->SetPageState(PageState::CreateFromURL(entry->GetURL()));
}

NavigationEntryImpl::RestoreType ControllerRestoreTypeToEntryType(
    NavigationController::RestoreType type) {
  switch (type) {
    case NavigationController::RESTORE_CURRENT_SESSION:
      return NavigationEntryImpl::RESTORE_CURRENT_SESSION;
    case NavigationController::RESTORE_LAST_SESSION_EXITED_CLEANLY:
      return NavigationEntryImpl::RESTORE_LAST_SESSION_EXITED_CLEANLY;
    case NavigationController::RESTORE_LAST_SESSION_CRASHED:
      return NavigationEntryImpl::RESTORE_LAST_SESSION_CRASHED;
  }
  NOTREACHED();
  return NavigationEntryImpl::RESTORE_CURRENT_SESSION;
}

// Configure all the NavigationEntries in entries for restore. This resets
// the transition type to reload and makes sure the content state isn't empty.
void ConfigureEntriesForRestore(
    std::vector<linked_ptr<NavigationEntryImpl> >* entries,
    NavigationController::RestoreType type) {
  for (size_t i = 0; i < entries->size(); ++i) {
    // Use a transition type of reload so that we don't incorrectly increase
    // the typed count.
    (*entries)[i]->SetTransitionType(PAGE_TRANSITION_RELOAD);
    (*entries)[i]->set_restore_type(ControllerRestoreTypeToEntryType(type));
    // NOTE(darin): This code is only needed for backwards compat.
    SetPageStateIfEmpty((*entries)[i].get());
  }
}

// See NavigationController::IsURLInPageNavigation for how this works and why.
bool AreURLsInPageNavigation(const GURL& existing_url,
                             const GURL& new_url,
                             bool renderer_says_in_page,
                             NavigationType navigation_type) {
  if (existing_url == new_url)
    return renderer_says_in_page;

  if (!new_url.has_ref()) {
    // When going back from the ref URL to the non ref one the navigation type
    // is IN_PAGE.
    return navigation_type == NAVIGATION_TYPE_IN_PAGE;
  }

  url_canon::Replacements<char> replacements;
  replacements.ClearRef();
  return existing_url.ReplaceComponents(replacements) ==
      new_url.ReplaceComponents(replacements);
}

// Determines whether or not we should be carrying over a user agent override
// between two NavigationEntries.
bool ShouldKeepOverride(const NavigationEntry* last_entry) {
  return last_entry && last_entry->GetIsOverridingUserAgent();
}

}  // namespace

// NavigationControllerImpl ----------------------------------------------------

const size_t kMaxEntryCountForTestingNotSet = -1;

// static
size_t NavigationControllerImpl::max_entry_count_for_testing_ =
    kMaxEntryCountForTestingNotSet;

// Should Reload check for post data? The default is true, but is set to false
// when testing.
static bool g_check_for_repost = true;

// static
NavigationEntry* NavigationController::CreateNavigationEntry(
      const GURL& url,
      const Referrer& referrer,
      PageTransition transition,
      bool is_renderer_initiated,
      const std::string& extra_headers,
      BrowserContext* browser_context) {
  // Allow the browser URL handler to rewrite the URL. This will, for example,
  // remove "view-source:" from the beginning of the URL to get the URL that
  // will actually be loaded. This real URL won't be shown to the user, just
  // used internally.
  GURL loaded_url(url);
  bool reverse_on_redirect = false;
  BrowserURLHandlerImpl::GetInstance()->RewriteURLIfNecessary(
      &loaded_url, browser_context, &reverse_on_redirect);

  NavigationEntryImpl* entry = new NavigationEntryImpl(
      NULL,  // The site instance for tabs is sent on navigation
             // (WebContents::GetSiteInstance).
      -1,
      loaded_url,
      referrer,
      base::string16(),
      transition,
      is_renderer_initiated);
  entry->SetVirtualURL(url);
  entry->set_user_typed_url(url);
  entry->set_update_virtual_url_with_url(reverse_on_redirect);
  entry->set_extra_headers(extra_headers);
  return entry;
}

// static
void NavigationController::DisablePromptOnRepost() {
  g_check_for_repost = false;
}

base::Time NavigationControllerImpl::TimeSmoother::GetSmoothedTime(
    base::Time t) {
  // If |t| is between the water marks, we're in a run of duplicates
  // or just getting out of it, so increase the high-water mark to get
  // a time that probably hasn't been used before and return it.
  if (low_water_mark_ <= t && t <= high_water_mark_) {
    high_water_mark_ += base::TimeDelta::FromMicroseconds(1);
    return high_water_mark_;
  }

  // Otherwise, we're clear of the last duplicate run, so reset the
  // water marks.
  low_water_mark_ = high_water_mark_ = t;
  return t;
}

NavigationControllerImpl::NavigationControllerImpl(
    NavigationControllerDelegate* delegate,
    BrowserContext* browser_context)
    : browser_context_(browser_context),
      pending_entry_(NULL),
      last_committed_entry_index_(-1),
      pending_entry_index_(-1),
      transient_entry_index_(-1),
      delegate_(delegate),
      max_restored_page_id_(-1),
      ssl_manager_(this),
      needs_reload_(false),
      is_initial_navigation_(true),
      in_navigate_to_pending_entry_(false),
      pending_reload_(NO_RELOAD),
      get_timestamp_callback_(base::Bind(&base::Time::Now)),
      screenshot_manager_(new NavigationEntryScreenshotManager(this)) {
  DCHECK(browser_context_);
}

NavigationControllerImpl::~NavigationControllerImpl() {
  DiscardNonCommittedEntriesInternal();
}

WebContents* NavigationControllerImpl::GetWebContents() const {
  return delegate_->GetWebContents();
}

BrowserContext* NavigationControllerImpl::GetBrowserContext() const {
  return browser_context_;
}

void NavigationControllerImpl::SetBrowserContext(
    BrowserContext* browser_context) {
  browser_context_ = browser_context;
}

void NavigationControllerImpl::Restore(
    int selected_navigation,
    RestoreType type,
    std::vector<NavigationEntry*>* entries) {
  // Verify that this controller is unused and that the input is valid.
  DCHECK(GetEntryCount() == 0 && !GetPendingEntry());
  DCHECK(selected_navigation >= 0 &&
         selected_navigation < static_cast<int>(entries->size()));

  needs_reload_ = true;
  for (size_t i = 0; i < entries->size(); ++i) {
    NavigationEntryImpl* entry =
        NavigationEntryImpl::FromNavigationEntry((*entries)[i]);
    entries_.push_back(linked_ptr<NavigationEntryImpl>(entry));
  }
  entries->clear();

  // And finish the restore.
  FinishRestore(selected_navigation, type);
}

void NavigationControllerImpl::Reload(bool check_for_repost) {
  ReloadInternal(check_for_repost, RELOAD);
}
void NavigationControllerImpl::ReloadIgnoringCache(bool check_for_repost) {
  ReloadInternal(check_for_repost, RELOAD_IGNORING_CACHE);
}
void NavigationControllerImpl::ReloadOriginalRequestURL(bool check_for_repost) {
  ReloadInternal(check_for_repost, RELOAD_ORIGINAL_REQUEST_URL);
}

void NavigationControllerImpl::ReloadInternal(bool check_for_repost,
                                              ReloadType reload_type) {
  if (transient_entry_index_ != -1) {
    // If an interstitial is showing, treat a reload as a navigation to the
    // transient entry's URL.
    NavigationEntryImpl* transient_entry =
        NavigationEntryImpl::FromNavigationEntry(GetTransientEntry());
    if (!transient_entry)
      return;
    LoadURL(transient_entry->GetURL(),
            Referrer(),
            PAGE_TRANSITION_RELOAD,
            transient_entry->extra_headers());
    return;
  }

  NavigationEntryImpl* entry = NULL;
  int current_index = -1;

  // If we are reloading the initial navigation, just use the current
  // pending entry.  Otherwise look up the current entry.
  if (IsInitialNavigation() && pending_entry_) {
    entry = pending_entry_;
    // The pending entry might be in entries_ (e.g., after a Clone), so we
    // should also update the current_index.
    current_index = pending_entry_index_;
  } else {
    DiscardNonCommittedEntriesInternal();
    current_index = GetCurrentEntryIndex();
    if (current_index != -1) {
      entry = NavigationEntryImpl::FromNavigationEntry(
          GetEntryAtIndex(current_index));
    }
  }

  // If we are no where, then we can't reload.  TODO(darin): We should add a
  // CanReload method.
  if (!entry)
    return;

  if (reload_type == NavigationControllerImpl::RELOAD_ORIGINAL_REQUEST_URL &&
      entry->GetOriginalRequestURL().is_valid() && !entry->GetHasPostData()) {
    // We may have been redirected when navigating to the current URL.
    // Use the URL the user originally intended to visit, if it's valid and if a
    // POST wasn't involved; the latter case avoids issues with sending data to
    // the wrong page.
    entry->SetURL(entry->GetOriginalRequestURL());
    entry->SetReferrer(Referrer());
  }

  if (g_check_for_repost && check_for_repost &&
      entry->GetHasPostData()) {
    // The user is asking to reload a page with POST data. Prompt to make sure
    // they really want to do this. If they do, the dialog will call us back
    // with check_for_repost = false.
    delegate_->NotifyBeforeFormRepostWarningShow();

    pending_reload_ = reload_type;
    delegate_->ActivateAndShowRepostFormWarningDialog();
  } else {
    if (!IsInitialNavigation())
      DiscardNonCommittedEntriesInternal();

    // If we are reloading an entry that no longer belongs to the current
    // site instance (for example, refreshing a page for just installed app),
    // the reload must happen in a new process.
    // The new entry must have a new page_id and site instance, so it behaves
    // as new navigation (which happens to clear forward history).
    // Tabs that are discarded due to low memory conditions may not have a site
    // instance, and should not be treated as a cross-site reload.
    SiteInstanceImpl* site_instance = entry->site_instance();
    // Permit reloading guests without further checks.
    bool is_guest = site_instance && site_instance->HasProcess() &&
                    site_instance->GetProcess()->IsGuest();
    if (!is_guest && site_instance &&
        site_instance->HasWrongProcessForURL(entry->GetURL())) {
      // Create a navigation entry that resembles the current one, but do not
      // copy page id, site instance, content state, or timestamp.
      NavigationEntryImpl* nav_entry = NavigationEntryImpl::FromNavigationEntry(
          CreateNavigationEntry(
              entry->GetURL(), entry->GetReferrer(), entry->GetTransitionType(),
              false, entry->extra_headers(), browser_context_));

      // Mark the reload type as NO_RELOAD, so navigation will not be considered
      // a reload in the renderer.
      reload_type = NavigationController::NO_RELOAD;

      nav_entry->set_should_replace_entry(true);
      pending_entry_ = nav_entry;
    } else {
      pending_entry_ = entry;
      pending_entry_index_ = current_index;

      // The title of the page being reloaded might have been removed in the
      // meanwhile, so we need to revert to the default title upon reload and
      // invalidate the previously cached title (SetTitle will do both).
      // See Chromium issue 96041.
      pending_entry_->SetTitle(base::string16());

      pending_entry_->SetTransitionType(PAGE_TRANSITION_RELOAD);
    }

    NavigateToPendingEntry(reload_type);
  }
}

void NavigationControllerImpl::CancelPendingReload() {
  DCHECK(pending_reload_ != NO_RELOAD);
  pending_reload_ = NO_RELOAD;
}

void NavigationControllerImpl::ContinuePendingReload() {
  if (pending_reload_ == NO_RELOAD) {
    NOTREACHED();
  } else {
    ReloadInternal(false, pending_reload_);
    pending_reload_ = NO_RELOAD;
  }
}

bool NavigationControllerImpl::IsInitialNavigation() const {
  return is_initial_navigation_;
}

NavigationEntryImpl* NavigationControllerImpl::GetEntryWithPageID(
  SiteInstance* instance, int32 page_id) const {
  int index = GetEntryIndexWithPageID(instance, page_id);
  return (index != -1) ? entries_[index].get() : NULL;
}

void NavigationControllerImpl::LoadEntry(NavigationEntryImpl* entry) {
  // When navigating to a new page, we don't know for sure if we will actually
  // end up leaving the current page.  The new page load could for example
  // result in a download or a 'no content' response (e.g., a mailto: URL).
  SetPendingEntry(entry);
  NavigateToPendingEntry(NO_RELOAD);
}

void NavigationControllerImpl::SetPendingEntry(NavigationEntryImpl* entry) {
  DiscardNonCommittedEntriesInternal();
  pending_entry_ = entry;
  NotificationService::current()->Notify(
      NOTIFICATION_NAV_ENTRY_PENDING,
      Source<NavigationController>(this),
      Details<NavigationEntry>(entry));
}

NavigationEntry* NavigationControllerImpl::GetActiveEntry() const {
  if (transient_entry_index_ != -1)
    return entries_[transient_entry_index_].get();
  if (pending_entry_)
    return pending_entry_;
  return GetLastCommittedEntry();
}

NavigationEntry* NavigationControllerImpl::GetVisibleEntry() const {
  if (transient_entry_index_ != -1)
    return entries_[transient_entry_index_].get();
  // The pending entry is safe to return for new (non-history), browser-
  // initiated navigations.  Most renderer-initiated navigations should not
  // show the pending entry, to prevent URL spoof attacks.
  //
  // We make an exception for renderer-initiated navigations in new tabs, as
  // long as no other page has tried to access the initial empty document in
  // the new tab.  If another page modifies this blank page, a URL spoof is
  // possible, so we must stop showing the pending entry.
  RenderViewHostImpl* rvh = static_cast<RenderViewHostImpl*>(
      delegate_->GetRenderViewHost());
  bool safe_to_show_pending =
      pending_entry_ &&
      // Require a new navigation.
      pending_entry_->GetPageID() == -1 &&
      // Require either browser-initiated or an unmodified new tab.
      (!pending_entry_->is_renderer_initiated() ||
       (IsInitialNavigation() &&
        !GetLastCommittedEntry() &&
        !rvh->has_accessed_initial_document()));

  // Also allow showing the pending entry for history navigations in a new tab,
  // such as Ctrl+Back.  In this case, no existing page is visible and no one
  // can script the new tab before it commits.
  if (!safe_to_show_pending &&
      pending_entry_ &&
      pending_entry_->GetPageID() != -1 &&
      IsInitialNavigation() &&
      !pending_entry_->is_renderer_initiated())
    safe_to_show_pending = true;

  if (safe_to_show_pending)
    return pending_entry_;
  return GetLastCommittedEntry();
}

int NavigationControllerImpl::GetCurrentEntryIndex() const {
  if (transient_entry_index_ != -1)
    return transient_entry_index_;
  if (pending_entry_index_ != -1)
    return pending_entry_index_;
  return last_committed_entry_index_;
}

NavigationEntry* NavigationControllerImpl::GetLastCommittedEntry() const {
  if (last_committed_entry_index_ == -1)
    return NULL;
  return entries_[last_committed_entry_index_].get();
}

bool NavigationControllerImpl::CanViewSource() const {
  const std::string& mime_type = delegate_->GetContentsMimeType();
  bool is_viewable_mime_type = net::IsSupportedNonImageMimeType(mime_type) &&
      !net::IsSupportedMediaMimeType(mime_type);
  NavigationEntry* visible_entry = GetVisibleEntry();
  return visible_entry && !visible_entry->IsViewSourceMode() &&
      is_viewable_mime_type && !delegate_->GetInterstitialPage();
}

int NavigationControllerImpl::GetLastCommittedEntryIndex() const {
  return last_committed_entry_index_;
}

int NavigationControllerImpl::GetEntryCount() const {
  DCHECK(entries_.size() <= max_entry_count());
  return static_cast<int>(entries_.size());
}

NavigationEntry* NavigationControllerImpl::GetEntryAtIndex(
    int index) const {
  return entries_.at(index).get();
}

NavigationEntry* NavigationControllerImpl::GetEntryAtOffset(
    int offset) const {
  int index = GetIndexForOffset(offset);
  if (index < 0 || index >= GetEntryCount())
    return NULL;

  return entries_[index].get();
}

int NavigationControllerImpl::GetIndexForOffset(int offset) const {
  return GetCurrentEntryIndex() + offset;
}

void NavigationControllerImpl::TakeScreenshot() {
  screenshot_manager_->TakeScreenshot();
}

void NavigationControllerImpl::SetScreenshotManager(
    NavigationEntryScreenshotManager* manager) {
  screenshot_manager_.reset(manager ? manager :
                            new NavigationEntryScreenshotManager(this));
}

bool NavigationControllerImpl::CanGoBack() const {
  return entries_.size() > 1 && GetCurrentEntryIndex() > 0;
}

bool NavigationControllerImpl::CanGoForward() const {
  int index = GetCurrentEntryIndex();
  return index >= 0 && index < (static_cast<int>(entries_.size()) - 1);
}

bool NavigationControllerImpl::CanGoToOffset(int offset) const {
  int index = GetIndexForOffset(offset);
  return index >= 0 && index < GetEntryCount();
}

void NavigationControllerImpl::GoBack() {
  if (!CanGoBack()) {
    NOTREACHED();
    return;
  }

  // Base the navigation on where we are now...
  int current_index = GetCurrentEntryIndex();

  DiscardNonCommittedEntries();

  pending_entry_index_ = current_index - 1;
  entries_[pending_entry_index_]->SetTransitionType(
      PageTransitionFromInt(
          entries_[pending_entry_index_]->GetTransitionType() |
          PAGE_TRANSITION_FORWARD_BACK));
  NavigateToPendingEntry(NO_RELOAD);
}

void NavigationControllerImpl::GoForward() {
  if (!CanGoForward()) {
    NOTREACHED();
    return;
  }

  bool transient = (transient_entry_index_ != -1);

  // Base the navigation on where we are now...
  int current_index = GetCurrentEntryIndex();

  DiscardNonCommittedEntries();

  pending_entry_index_ = current_index;
  // If there was a transient entry, we removed it making the current index
  // the next page.
  if (!transient)
    pending_entry_index_++;

  entries_[pending_entry_index_]->SetTransitionType(
      PageTransitionFromInt(
          entries_[pending_entry_index_]->GetTransitionType() |
          PAGE_TRANSITION_FORWARD_BACK));
  NavigateToPendingEntry(NO_RELOAD);
}

void NavigationControllerImpl::GoToIndex(int index) {
  if (index < 0 || index >= static_cast<int>(entries_.size())) {
    NOTREACHED();
    return;
  }

  if (transient_entry_index_ != -1) {
    if (index == transient_entry_index_) {
      // Nothing to do when navigating to the transient.
      return;
    }
    if (index > transient_entry_index_) {
      // Removing the transient is goint to shift all entries by 1.
      index--;
    }
  }

  DiscardNonCommittedEntries();

  pending_entry_index_ = index;
  entries_[pending_entry_index_]->SetTransitionType(
      PageTransitionFromInt(
          entries_[pending_entry_index_]->GetTransitionType() |
          PAGE_TRANSITION_FORWARD_BACK));
  NavigateToPendingEntry(NO_RELOAD);
}

void NavigationControllerImpl::GoToOffset(int offset) {
  if (!CanGoToOffset(offset))
    return;

  GoToIndex(GetIndexForOffset(offset));
}

bool NavigationControllerImpl::RemoveEntryAtIndex(int index) {
  if (index == last_committed_entry_index_ ||
      index == pending_entry_index_)
    return false;

  RemoveEntryAtIndexInternal(index);
  return true;
}

void NavigationControllerImpl::UpdateVirtualURLToURL(
    NavigationEntryImpl* entry, const GURL& new_url) {
  GURL new_virtual_url(new_url);
  if (BrowserURLHandlerImpl::GetInstance()->ReverseURLRewrite(
          &new_virtual_url, entry->GetVirtualURL(), browser_context_)) {
    entry->SetVirtualURL(new_virtual_url);
  }
}

void NavigationControllerImpl::LoadURL(
    const GURL& url,
    const Referrer& referrer,
    PageTransition transition,
    const std::string& extra_headers) {
  LoadURLParams params(url);
  params.referrer = referrer;
  params.transition_type = transition;
  params.extra_headers = extra_headers;
  LoadURLWithParams(params);
}

void NavigationControllerImpl::LoadURLWithParams(const LoadURLParams& params) {
  TRACE_EVENT0("browser", "NavigationControllerImpl::LoadURLWithParams");
  if (HandleDebugURL(params.url, params.transition_type))
    return;

  // Any renderer-side debug URLs or javascript: URLs should be ignored if the
  // renderer process is not live, unless it is the initial navigation of the
  // tab.
  if (IsRendererDebugURL(params.url)) {
    // TODO(creis): Find the RVH for the correct frame.
    if (!delegate_->GetRenderViewHost()->IsRenderViewLive() &&
        !IsInitialNavigation())
      return;
  }

  // Checks based on params.load_type.
  switch (params.load_type) {
    case LOAD_TYPE_DEFAULT:
      break;
    case LOAD_TYPE_BROWSER_INITIATED_HTTP_POST:
      if (!params.url.SchemeIs(kHttpScheme) &&
          !params.url.SchemeIs(kHttpsScheme)) {
        NOTREACHED() << "Http post load must use http(s) scheme.";
        return;
      }
      break;
    case LOAD_TYPE_DATA:
      if (!params.url.SchemeIs(kDataScheme)) {
        NOTREACHED() << "Data load must use data scheme.";
        return;
      }
      break;
    default:
      NOTREACHED();
      break;
  };

  // The user initiated a load, we don't need to reload anymore.
  needs_reload_ = false;

  bool override = false;
  switch (params.override_user_agent) {
    case UA_OVERRIDE_INHERIT:
      override = ShouldKeepOverride(GetLastCommittedEntry());
      break;
    case UA_OVERRIDE_TRUE:
      override = true;
      break;
    case UA_OVERRIDE_FALSE:
      override = false;
      break;
    default:
      NOTREACHED();
      break;
  }

  NavigationEntryImpl* entry = NavigationEntryImpl::FromNavigationEntry(
      CreateNavigationEntry(
          params.url,
          params.referrer,
          params.transition_type,
          params.is_renderer_initiated,
          params.extra_headers,
          browser_context_));
  if (params.frame_tree_node_id != -1)
    entry->set_frame_tree_node_id(params.frame_tree_node_id);
  if (params.redirect_chain.size() > 0)
    entry->set_redirect_chain(params.redirect_chain);
  if (params.should_replace_current_entry)
    entry->set_should_replace_entry(true);
  entry->set_should_clear_history_list(params.should_clear_history_list);
  entry->SetIsOverridingUserAgent(override);
  entry->set_transferred_global_request_id(
      params.transferred_global_request_id);
  entry->SetFrameToNavigate(params.frame_name);

  switch (params.load_type) {
    case LOAD_TYPE_DEFAULT:
      break;
    case LOAD_TYPE_BROWSER_INITIATED_HTTP_POST:
      entry->SetHasPostData(true);
      entry->SetBrowserInitiatedPostData(
          params.browser_initiated_post_data.get());
      break;
    case LOAD_TYPE_DATA:
      entry->SetBaseURLForDataURL(params.base_url_for_data_url);
      entry->SetVirtualURL(params.virtual_url_for_data_url);
      entry->SetCanLoadLocalResources(params.can_load_local_resources);
      break;
    default:
      NOTREACHED();
      break;
  };

  LoadEntry(entry);
}

bool NavigationControllerImpl::RendererDidNavigate(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params,
    LoadCommittedDetails* details) {
  is_initial_navigation_ = false;

  // Save the previous state before we clobber it.
  if (GetLastCommittedEntry()) {
    details->previous_url = GetLastCommittedEntry()->GetURL();
    details->previous_entry_index = GetLastCommittedEntryIndex();
  } else {
    details->previous_url = GURL();
    details->previous_entry_index = -1;
  }

  // If we have a pending entry at this point, it should have a SiteInstance.
  // Restored entries start out with a null SiteInstance, but we should have
  // assigned one in NavigateToPendingEntry.
  DCHECK(pending_entry_index_ == -1 || pending_entry_->site_instance());

  // If we are doing a cross-site reload, we need to replace the existing
  // navigation entry, not add another entry to the history. This has the side
  // effect of removing forward browsing history, if such existed.
  // Or if we are doing a cross-site redirect navigation,
  // we will do a similar thing.
  details->did_replace_entry =
      pending_entry_ && pending_entry_->should_replace_entry();

  // Do navigation-type specific actions. These will make and commit an entry.
  details->type = ClassifyNavigation(rfh, params);

  // is_in_page must be computed before the entry gets committed.
  details->is_in_page = IsURLInPageNavigation(
      params.url, params.was_within_same_page, details->type);

  switch (details->type) {
    case NAVIGATION_TYPE_NEW_PAGE:
      RendererDidNavigateToNewPage(rfh, params, details->did_replace_entry);
      break;
    case NAVIGATION_TYPE_EXISTING_PAGE:
      RendererDidNavigateToExistingPage(rfh, params);
      break;
    case NAVIGATION_TYPE_SAME_PAGE:
      RendererDidNavigateToSamePage(rfh, params);
      break;
    case NAVIGATION_TYPE_IN_PAGE:
      RendererDidNavigateInPage(rfh, params, &details->did_replace_entry);
      break;
    case NAVIGATION_TYPE_NEW_SUBFRAME:
      RendererDidNavigateNewSubframe(rfh, params);
      break;
    case NAVIGATION_TYPE_AUTO_SUBFRAME:
      if (!RendererDidNavigateAutoSubframe(rfh, params))
        return false;
      break;
    case NAVIGATION_TYPE_NAV_IGNORE:
      // If a pending navigation was in progress, this canceled it.  We should
      // discard it and make sure it is removed from the URL bar.  After that,
      // there is nothing we can do with this navigation, so we just return to
      // the caller that nothing has happened.
      if (pending_entry_) {
        DiscardNonCommittedEntries();
        delegate_->NotifyNavigationStateChanged(INVALIDATE_TYPE_URL);
      }
      return false;
    default:
      NOTREACHED();
  }

  // At this point, we know that the navigation has just completed, so
  // record the time.
  //
  // TODO(akalin): Use "sane time" as described in
  // http://www.chromium.org/developers/design-documents/sane-time .
  base::Time timestamp =
      time_smoother_.GetSmoothedTime(get_timestamp_callback_.Run());
  DVLOG(1) << "Navigation finished at (smoothed) timestamp "
           << timestamp.ToInternalValue();

  // We should not have a pending entry anymore.  Clear it again in case any
  // error cases above forgot to do so.
  DiscardNonCommittedEntriesInternal();

  // All committed entries should have nonempty content state so WebKit doesn't
  // get confused when we go back to them (see the function for details).
  DCHECK(params.page_state.IsValid());
  NavigationEntryImpl* active_entry =
      NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
  active_entry->SetTimestamp(timestamp);
  active_entry->SetHttpStatusCode(params.http_status_code);
  active_entry->SetPageState(params.page_state);

  // Once it is committed, we no longer need to track several pieces of state on
  // the entry.
  active_entry->ResetForCommit();

  // The active entry's SiteInstance should match our SiteInstance.
  // TODO(creis): This check won't pass for subframes until we create entries
  // for subframe navigations.
  if (PageTransitionIsMainFrame(params.transition))
    CHECK(active_entry->site_instance() == rfh->GetSiteInstance());

  // Remember the bindings the renderer process has at this point, so that
  // we do not grant this entry additional bindings if we come back to it.
  active_entry->SetBindings(
      static_cast<RenderFrameHostImpl*>(rfh)->GetEnabledBindings());

  // Now prep the rest of the details for the notification and broadcast.
  details->entry = active_entry;
  details->is_main_frame =
      PageTransitionIsMainFrame(params.transition);
  details->serialized_security_info = params.security_info;
  details->http_status_code = params.http_status_code;
  NotifyNavigationEntryCommitted(details);

  return true;
}

NavigationType NavigationControllerImpl::ClassifyNavigation(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params) const {
  if (params.page_id == -1) {
    // The renderer generates the page IDs, and so if it gives us the invalid
    // page ID (-1) we know it didn't actually navigate. This happens in a few
    // cases:
    //
    // - If a page makes a popup navigated to about blank, and then writes
    //   stuff like a subframe navigated to a real page. We'll get the commit
    //   for the subframe, but there won't be any commit for the outer page.
    //
    // - We were also getting these for failed loads (for example, bug 21849).
    //   The guess is that we get a "load commit" for the alternate error page,
    //   but that doesn't affect the page ID, so we get the "old" one, which
    //   could be invalid. This can also happen for a cross-site transition
    //   that causes us to swap processes. Then the error page load will be in
    //   a new process with no page IDs ever assigned (and hence a -1 value),
    //   yet the navigation controller still might have previous pages in its
    //   list.
    //
    // In these cases, there's nothing we can do with them, so ignore.
    return NAVIGATION_TYPE_NAV_IGNORE;
  }

  if (params.page_id > delegate_->GetMaxPageIDForSiteInstance(
          rfh->GetSiteInstance())) {
    // Greater page IDs than we've ever seen before are new pages. We may or may
    // not have a pending entry for the page, and this may or may not be the
    // main frame.
    if (PageTransitionIsMainFrame(params.transition))
      return NAVIGATION_TYPE_NEW_PAGE;

    // When this is a new subframe navigation, we should have a committed page
    // for which it's a suframe in. This may not be the case when an iframe is
    // navigated on a popup navigated to about:blank (the iframe would be
    // written into the popup by script on the main page). For these cases,
    // there isn't any navigation stuff we can do, so just ignore it.
    if (!GetLastCommittedEntry())
      return NAVIGATION_TYPE_NAV_IGNORE;

    // Valid subframe navigation.
    return NAVIGATION_TYPE_NEW_SUBFRAME;
  }

  // We only clear the session history when navigating to a new page.
  DCHECK(!params.history_list_was_cleared);

  // Now we know that the notification is for an existing page. Find that entry.
  int existing_entry_index = GetEntryIndexWithPageID(
      rfh->GetSiteInstance(),
      params.page_id);
  if (existing_entry_index == -1) {
    // The page was not found. It could have been pruned because of the limit on
    // back/forward entries (not likely since we'll usually tell it to navigate
    // to such entries). It could also mean that the renderer is smoking crack.
    NOTREACHED();

    // Because the unknown entry has committed, we risk showing the wrong URL in
    // release builds. Instead, we'll kill the renderer process to be safe.
    LOG(ERROR) << "terminating renderer for bad navigation: " << params.url;
    RecordAction(base::UserMetricsAction("BadMessageTerminate_NC"));

    // Temporary code so we can get more information.  Format:
    //  http://url/foo.html#page1#max3#frame1#ids:2_Nx,1_1x,3_2
    std::string temp = params.url.spec();
    temp.append("#page");
    temp.append(base::IntToString(params.page_id));
    temp.append("#max");
    temp.append(base::IntToString(delegate_->GetMaxPageID()));
    temp.append("#frame");
    temp.append(base::IntToString(rfh->GetRoutingID()));
    temp.append("#ids");
    for (int i = 0; i < static_cast<int>(entries_.size()); ++i) {
      // Append entry metadata (e.g., 3_7x):
      //  3: page_id
      //  7: SiteInstance ID, or N for null
      //  x: appended if not from the current SiteInstance
      temp.append(base::IntToString(entries_[i]->GetPageID()));
      temp.append("_");
      if (entries_[i]->site_instance())
        temp.append(base::IntToString(entries_[i]->site_instance()->GetId()));
      else
        temp.append("N");
      if (entries_[i]->site_instance() != rfh->GetSiteInstance())
        temp.append("x");
      temp.append(",");
    }
    GURL url(temp);
    static_cast<RenderFrameHostImpl*>(rfh)->render_view_host()->Send(
        new ViewMsg_TempCrashWithData(url));
    return NAVIGATION_TYPE_NAV_IGNORE;
  }
  NavigationEntryImpl* existing_entry = entries_[existing_entry_index].get();

  if (!PageTransitionIsMainFrame(params.transition)) {
    // All manual subframes would get new IDs and were handled above, so we
    // know this is auto. Since the current page was found in the navigation
    // entry list, we're guaranteed to have a last committed entry.
    DCHECK(GetLastCommittedEntry());
    return NAVIGATION_TYPE_AUTO_SUBFRAME;
  }

  // Anything below here we know is a main frame navigation.
  if (pending_entry_ &&
      !pending_entry_->is_renderer_initiated() &&
      existing_entry != pending_entry_ &&
      pending_entry_->GetPageID() == -1 &&
      existing_entry == GetLastCommittedEntry()) {
    // In this case, we have a pending entry for a URL but WebCore didn't do a
    // new navigation. This happens when you press enter in the URL bar to
    // reload. We will create a pending entry, but WebKit will convert it to
    // a reload since it's the same page and not create a new entry for it
    // (the user doesn't want to have a new back/forward entry when they do
    // this). If this matches the last committed entry, we want to just ignore
    // the pending entry and go back to where we were (the "existing entry").
    return NAVIGATION_TYPE_SAME_PAGE;
  }

  // Any toplevel navigations with the same base (minus the reference fragment)
  // are in-page navigations. We weeded out subframe navigations above. Most of
  // the time this doesn't matter since WebKit doesn't tell us about subframe
  // navigations that don't actually navigate, but it can happen when there is
  // an encoding override (it always sends a navigation request).
  if (AreURLsInPageNavigation(existing_entry->GetURL(), params.url,
                              params.was_within_same_page,
                              NAVIGATION_TYPE_UNKNOWN)) {
    return NAVIGATION_TYPE_IN_PAGE;
  }

  // Since we weeded out "new" navigations above, we know this is an existing
  // (back/forward) navigation.
  return NAVIGATION_TYPE_EXISTING_PAGE;
}

void NavigationControllerImpl::RendererDidNavigateToNewPage(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params,
    bool replace_entry) {
  NavigationEntryImpl* new_entry;
  bool update_virtual_url;
  // Only make a copy of the pending entry if it is appropriate for the new page
  // that was just loaded.  We verify this at a coarse grain by checking that
  // the SiteInstance hasn't been assigned to something else.
  if (pending_entry_ &&
      (!pending_entry_->site_instance() ||
       pending_entry_->site_instance() == rfh->GetSiteInstance())) {
    new_entry = new NavigationEntryImpl(*pending_entry_);

    // Don't use the page type from the pending entry. Some interstitial page
    // may have set the type to interstitial. Once we commit, however, the page
    // type must always be normal.
    new_entry->set_page_type(PAGE_TYPE_NORMAL);
    update_virtual_url = new_entry->update_virtual_url_with_url();
  } else {
    new_entry = new NavigationEntryImpl;

    // Find out whether the new entry needs to update its virtual URL on URL
    // change and set up the entry accordingly. This is needed to correctly
    // update the virtual URL when replaceState is called after a pushState.
    GURL url = params.url;
    bool needs_update = false;
    BrowserURLHandlerImpl::GetInstance()->RewriteURLIfNecessary(
        &url, browser_context_, &needs_update);
    new_entry->set_update_virtual_url_with_url(needs_update);

    // When navigating to a new page, give the browser URL handler a chance to
    // update the virtual URL based on the new URL. For example, this is needed
    // to show chrome://bookmarks/#1 when the bookmarks webui extension changes
    // the URL.
    update_virtual_url = needs_update;
  }

  new_entry->SetURL(params.url);
  if (update_virtual_url)
    UpdateVirtualURLToURL(new_entry, params.url);
  new_entry->SetReferrer(params.referrer);
  new_entry->SetPageID(params.page_id);
  new_entry->SetTransitionType(params.transition);
  new_entry->set_site_instance(
      static_cast<SiteInstanceImpl*>(rfh->GetSiteInstance()));
  new_entry->SetHasPostData(params.is_post);
  new_entry->SetPostID(params.post_id);
  new_entry->SetOriginalRequestURL(params.original_request_url);
  new_entry->SetIsOverridingUserAgent(params.is_overriding_user_agent);

  DCHECK(!params.history_list_was_cleared || !replace_entry);
  // The browser requested to clear the session history when it initiated the
  // navigation. Now we know that the renderer has updated its state accordingly
  // and it is safe to also clear the browser side history.
  if (params.history_list_was_cleared) {
    DiscardNonCommittedEntriesInternal();
    entries_.clear();
    last_committed_entry_index_ = -1;
  }

  InsertOrReplaceEntry(new_entry, replace_entry);
}

void NavigationControllerImpl::RendererDidNavigateToExistingPage(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params) {
  // We should only get here for main frame navigations.
  DCHECK(PageTransitionIsMainFrame(params.transition));

  // This is a back/forward navigation. The existing page for the ID is
  // guaranteed to exist by ClassifyNavigation, and we just need to update it
  // with new information from the renderer.
  int entry_index = GetEntryIndexWithPageID(rfh->GetSiteInstance(),
                                            params.page_id);
  DCHECK(entry_index >= 0 &&
         entry_index < static_cast<int>(entries_.size()));
  NavigationEntryImpl* entry = entries_[entry_index].get();

  // The URL may have changed due to redirects.
  entry->SetURL(params.url);
  entry->SetReferrer(params.referrer);
  if (entry->update_virtual_url_with_url())
    UpdateVirtualURLToURL(entry, params.url);

  // The redirected to page should not inherit the favicon from the previous
  // page.
  if (PageTransitionIsRedirect(params.transition))
    entry->GetFavicon() = FaviconStatus();

  // The site instance will normally be the same except during session restore,
  // when no site instance will be assigned.
  DCHECK(entry->site_instance() == NULL ||
         entry->site_instance() == rfh->GetSiteInstance());
  entry->set_site_instance(
      static_cast<SiteInstanceImpl*>(rfh->GetSiteInstance()));

  entry->SetHasPostData(params.is_post);
  entry->SetPostID(params.post_id);

  // The entry we found in the list might be pending if the user hit
  // back/forward/reload. This load should commit it (since it's already in the
  // list, we can just discard the pending pointer).  We should also discard the
  // pending entry if it corresponds to a different navigation, since that one
  // is now likely canceled.  If it is not canceled, we will treat it as a new
  // navigation when it arrives, which is also ok.
  //
  // Note that we need to use the "internal" version since we don't want to
  // actually change any other state, just kill the pointer.
  DiscardNonCommittedEntriesInternal();

  // If a transient entry was removed, the indices might have changed, so we
  // have to query the entry index again.
  last_committed_entry_index_ =
      GetEntryIndexWithPageID(rfh->GetSiteInstance(), params.page_id);
}

void NavigationControllerImpl::RendererDidNavigateToSamePage(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params) {
  // This mode implies we have a pending entry that's the same as an existing
  // entry for this page ID. This entry is guaranteed to exist by
  // ClassifyNavigation. All we need to do is update the existing entry.
  NavigationEntryImpl* existing_entry = GetEntryWithPageID(
      rfh->GetSiteInstance(), params.page_id);

  // We assign the entry's unique ID to be that of the new one. Since this is
  // always the result of a user action, we want to dismiss infobars, etc. like
  // a regular user-initiated navigation.
  existing_entry->set_unique_id(pending_entry_->GetUniqueID());

  // The URL may have changed due to redirects.
  if (existing_entry->update_virtual_url_with_url())
    UpdateVirtualURLToURL(existing_entry, params.url);
  existing_entry->SetURL(params.url);
  existing_entry->SetReferrer(params.referrer);

  // The page may have been requested with a different HTTP method.
  existing_entry->SetHasPostData(params.is_post);
  existing_entry->SetPostID(params.post_id);

  DiscardNonCommittedEntries();
}

void NavigationControllerImpl::RendererDidNavigateInPage(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params,
    bool* did_replace_entry) {
  DCHECK(PageTransitionIsMainFrame(params.transition)) <<
      "WebKit should only tell us about in-page navs for the main frame.";
  // We're guaranteed to have an entry for this one.
  NavigationEntryImpl* existing_entry = GetEntryWithPageID(
      rfh->GetSiteInstance(), params.page_id);

  // Reference fragment navigation. We're guaranteed to have the last_committed
  // entry and it will be the same page as the new navigation (minus the
  // reference fragments, of course).  We'll update the URL of the existing
  // entry without pruning the forward history.
  existing_entry->SetURL(params.url);
  if (existing_entry->update_virtual_url_with_url())
    UpdateVirtualURLToURL(existing_entry, params.url);

  // This replaces the existing entry since the page ID didn't change.
  *did_replace_entry = true;

  DiscardNonCommittedEntriesInternal();

  // If a transient entry was removed, the indices might have changed, so we
  // have to query the entry index again.
  last_committed_entry_index_ =
      GetEntryIndexWithPageID(rfh->GetSiteInstance(), params.page_id);
}

void NavigationControllerImpl::RendererDidNavigateNewSubframe(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params) {
  if (PageTransitionCoreTypeIs(params.transition,
                               PAGE_TRANSITION_AUTO_SUBFRAME)) {
    // This is not user-initiated. Ignore.
    DiscardNonCommittedEntriesInternal();
    return;
  }

  // Manual subframe navigations just get the current entry cloned so the user
  // can go back or forward to it. The actual subframe information will be
  // stored in the page state for each of those entries. This happens out of
  // band with the actual navigations.
  DCHECK(GetLastCommittedEntry()) << "ClassifyNavigation should guarantee "
                                  << "that a last committed entry exists.";
  NavigationEntryImpl* new_entry = new NavigationEntryImpl(
      *NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry()));
  new_entry->SetPageID(params.page_id);
  InsertOrReplaceEntry(new_entry, false);
}

bool NavigationControllerImpl::RendererDidNavigateAutoSubframe(
    RenderFrameHost* rfh,
    const FrameHostMsg_DidCommitProvisionalLoad_Params& params) {
  // We're guaranteed to have a previously committed entry, and we now need to
  // handle navigation inside of a subframe in it without creating a new entry.
  DCHECK(GetLastCommittedEntry());

  // Handle the case where we're navigating back/forward to a previous subframe
  // navigation entry. This is case "2." in NAV_AUTO_SUBFRAME comment in the
  // header file. In case "1." this will be a NOP.
  int entry_index = GetEntryIndexWithPageID(
      rfh->GetSiteInstance(),
      params.page_id);
  if (entry_index < 0 ||
      entry_index >= static_cast<int>(entries_.size())) {
    NOTREACHED();
    return false;
  }

  // Update the current navigation entry in case we're going back/forward.
  if (entry_index != last_committed_entry_index_) {
    last_committed_entry_index_ = entry_index;
    DiscardNonCommittedEntriesInternal();
    return true;
  }

  // We do not need to discard the pending entry in this case, since we will
  // not generate commit notifications for this auto-subframe navigation.
  return false;
}

int NavigationControllerImpl::GetIndexOfEntry(
    const NavigationEntryImpl* entry) const {
  const NavigationEntries::const_iterator i(std::find(
      entries_.begin(),
      entries_.end(),
      entry));
  return (i == entries_.end()) ? -1 : static_cast<int>(i - entries_.begin());
}

bool NavigationControllerImpl::IsURLInPageNavigation(
    const GURL& url,
    bool renderer_says_in_page,
    NavigationType navigation_type) const {
  NavigationEntry* last_committed = GetLastCommittedEntry();
  return last_committed && AreURLsInPageNavigation(
      last_committed->GetURL(), url, renderer_says_in_page, navigation_type);
}

void NavigationControllerImpl::CopyStateFrom(
    const NavigationController& temp) {
  const NavigationControllerImpl& source =
      static_cast<const NavigationControllerImpl&>(temp);
  // Verify that we look new.
  DCHECK(GetEntryCount() == 0 && !GetPendingEntry());

  if (source.GetEntryCount() == 0)
    return;  // Nothing new to do.

  needs_reload_ = true;
  InsertEntriesFrom(source, source.GetEntryCount());

  for (SessionStorageNamespaceMap::const_iterator it =
           source.session_storage_namespace_map_.begin();
       it != source.session_storage_namespace_map_.end();
       ++it) {
    SessionStorageNamespaceImpl* source_namespace =
        static_cast<SessionStorageNamespaceImpl*>(it->second.get());
    session_storage_namespace_map_[it->first] = source_namespace->Clone();
  }

  FinishRestore(source.last_committed_entry_index_, RESTORE_CURRENT_SESSION);

  // Copy the max page id map from the old tab to the new tab.  This ensures
  // that new and existing navigations in the tab's current SiteInstances
  // are identified properly.
  delegate_->CopyMaxPageIDsFrom(source.delegate()->GetWebContents());
}

void NavigationControllerImpl::CopyStateFromAndPrune(
    NavigationController* temp,
    bool replace_entry) {
  // It is up to callers to check the invariants before calling this.
  CHECK(CanPruneAllButLastCommitted());

  NavigationControllerImpl* source =
      static_cast<NavigationControllerImpl*>(temp);
  // The SiteInstance and page_id of the last committed entry needs to be
  // remembered at this point, in case there is only one committed entry
  // and it is pruned.  We use a scoped_refptr to ensure the SiteInstance
  // can't be freed during this time period.
  NavigationEntryImpl* last_committed =
      NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
  scoped_refptr<SiteInstance> site_instance(
      last_committed->site_instance());
  int32 minimum_page_id = last_committed->GetPageID();
  int32 max_page_id =
      delegate_->GetMaxPageIDForSiteInstance(site_instance.get());

  // Remove all the entries leaving the active entry.
  PruneAllButLastCommittedInternal();

  // We now have one entry, possibly with a new pending entry.  Ensure that
  // adding the entries from source won't put us over the limit.
  DCHECK_EQ(1, GetEntryCount());
  if (!replace_entry)
    source->PruneOldestEntryIfFull();

  // Insert the entries from source. Don't use source->GetCurrentEntryIndex as
  // we don't want to copy over the transient entry.  Ignore any pending entry,
  // since it has not committed in source.
  int max_source_index = source->last_committed_entry_index_;
  if (max_source_index == -1)
    max_source_index = source->GetEntryCount();
  else
    max_source_index++;

  // Ignore the source's current entry if merging with replacement.
  // TODO(davidben): This should preserve entries forward of the current
  // too. http://crbug.com/317872
  if (replace_entry && max_source_index > 0)
    max_source_index--;

  InsertEntriesFrom(*source, max_source_index);

  // Adjust indices such that the last entry and pending are at the end now.
  last_committed_entry_index_ = GetEntryCount() - 1;

  delegate_->SetHistoryLengthAndPrune(site_instance.get(),
                                      max_source_index,
                                      minimum_page_id);

  // Copy the max page id map from the old tab to the new tab.  This ensures
  // that new and existing navigations in the tab's current SiteInstances
  // are identified properly.
  delegate_->CopyMaxPageIDsFrom(source->delegate()->GetWebContents());

  // If there is a last committed entry, be sure to include it in the new
  // max page ID map.
  if (max_page_id > -1) {
    delegate_->UpdateMaxPageIDForSiteInstance(site_instance.get(),
                                              max_page_id);
  }
}

bool NavigationControllerImpl::CanPruneAllButLastCommitted() {
  // If there is no last committed entry, we cannot prune.  Even if there is a
  // pending entry, it may not commit, leaving this WebContents blank, despite
  // possibly giving it new entries via CopyStateFromAndPrune.
  if (last_committed_entry_index_ == -1)
    return false;

  // We cannot prune if there is a pending entry at an existing entry index.
  // It may not commit, so we have to keep the last committed entry, and thus
  // there is no sensible place to keep the pending entry.  It is ok to have
  // a new pending entry, which can optionally commit as a new navigation.
  if (pending_entry_index_ != -1)
    return false;

  // We should not prune if we are currently showing a transient entry.
  if (transient_entry_index_ != -1)
    return false;

  return true;
}

void NavigationControllerImpl::PruneAllButLastCommitted() {
  PruneAllButLastCommittedInternal();

  // We should still have a last committed entry.
  DCHECK_NE(-1, last_committed_entry_index_);

  // We pass 0 instead of GetEntryCount() for the history_length parameter of
  // SetHistoryLengthAndPrune, because it will create history_length additional
  // history entries.
  // TODO(jochen): This API is confusing and we should clean it up.
  // http://crbug.com/178491
  NavigationEntryImpl* entry =
      NavigationEntryImpl::FromNavigationEntry(GetVisibleEntry());
  delegate_->SetHistoryLengthAndPrune(
      entry->site_instance(), 0, entry->GetPageID());
}

void NavigationControllerImpl::PruneAllButLastCommittedInternal() {
  // It is up to callers to check the invariants before calling this.
  CHECK(CanPruneAllButLastCommitted());

  // Erase all entries but the last committed entry.  There may still be a
  // new pending entry after this.
  entries_.erase(entries_.begin(),
                 entries_.begin() + last_committed_entry_index_);
  entries_.erase(entries_.begin() + 1, entries_.end());
  last_committed_entry_index_ = 0;
}

void NavigationControllerImpl::ClearAllScreenshots() {
  screenshot_manager_->ClearAllScreenshots();
}

void NavigationControllerImpl::SetSessionStorageNamespace(
    const std::string& partition_id,
    SessionStorageNamespace* session_storage_namespace) {
  if (!session_storage_namespace)
    return;

  // We can't overwrite an existing SessionStorage without violating spec.
  // Attempts to do so may give a tab access to another tab's session storage
  // so die hard on an error.
  bool successful_insert = session_storage_namespace_map_.insert(
      make_pair(partition_id,
                static_cast<SessionStorageNamespaceImpl*>(
                    session_storage_namespace)))
          .second;
  CHECK(successful_insert) << "Cannot replace existing SessionStorageNamespace";
}

void NavigationControllerImpl::SetMaxRestoredPageID(int32 max_id) {
  max_restored_page_id_ = max_id;
}

int32 NavigationControllerImpl::GetMaxRestoredPageID() const {
  return max_restored_page_id_;
}

SessionStorageNamespace*
NavigationControllerImpl::GetSessionStorageNamespace(SiteInstance* instance) {
  std::string partition_id;
  if (instance) {
    // TODO(ajwong): When GetDefaultSessionStorageNamespace() goes away, remove
    // this if statement so |instance| must not be NULL.
    partition_id =
        GetContentClient()->browser()->GetStoragePartitionIdForSite(
            browser_context_, instance->GetSiteURL());
  }

  SessionStorageNamespaceMap::const_iterator it =
      session_storage_namespace_map_.find(partition_id);
  if (it != session_storage_namespace_map_.end())
    return it->second.get();

  // Create one if no one has accessed session storage for this partition yet.
  //
  // TODO(ajwong): Should this use the |partition_id| directly rather than
  // re-lookup via |instance|?  http://crbug.com/142685
  StoragePartition* partition =
              BrowserContext::GetStoragePartition(browser_context_, instance);
  SessionStorageNamespaceImpl* session_storage_namespace =
      new SessionStorageNamespaceImpl(
          static_cast<DOMStorageContextWrapper*>(
              partition->GetDOMStorageContext()));
  session_storage_namespace_map_[partition_id] = session_storage_namespace;

  return session_storage_namespace;
}

SessionStorageNamespace*
NavigationControllerImpl::GetDefaultSessionStorageNamespace() {
  // TODO(ajwong): Remove if statement in GetSessionStorageNamespace().
  return GetSessionStorageNamespace(NULL);
}

const SessionStorageNamespaceMap&
NavigationControllerImpl::GetSessionStorageNamespaceMap() const {
  return session_storage_namespace_map_;
}

bool NavigationControllerImpl::NeedsReload() const {
  return needs_reload_;
}

void NavigationControllerImpl::SetNeedsReload() {
  needs_reload_ = true;
}

void NavigationControllerImpl::RemoveEntryAtIndexInternal(int index) {
  DCHECK(index < GetEntryCount());
  DCHECK(index != last_committed_entry_index_);

  DiscardNonCommittedEntries();

  entries_.erase(entries_.begin() + index);
  if (last_committed_entry_index_ > index)
    last_committed_entry_index_--;
}

void NavigationControllerImpl::DiscardNonCommittedEntries() {
  bool transient = transient_entry_index_ != -1;
  DiscardNonCommittedEntriesInternal();

  // If there was a transient entry, invalidate everything so the new active
  // entry state is shown.
  if (transient) {
    delegate_->NotifyNavigationStateChanged(kInvalidateAll);
  }
}

NavigationEntry* NavigationControllerImpl::GetPendingEntry() const {
  return pending_entry_;
}

int NavigationControllerImpl::GetPendingEntryIndex() const {
  return pending_entry_index_;
}

void NavigationControllerImpl::InsertOrReplaceEntry(NavigationEntryImpl* entry,
                                                    bool replace) {
  DCHECK(entry->GetTransitionType() != PAGE_TRANSITION_AUTO_SUBFRAME);

  // Copy the pending entry's unique ID to the committed entry.
  // I don't know if pending_entry_index_ can be other than -1 here.
  const NavigationEntryImpl* const pending_entry =
      (pending_entry_index_ == -1) ?
          pending_entry_ : entries_[pending_entry_index_].get();
  if (pending_entry)
    entry->set_unique_id(pending_entry->GetUniqueID());

  DiscardNonCommittedEntriesInternal();

  int current_size = static_cast<int>(entries_.size());

  if (current_size > 0) {
    // Prune any entries which are in front of the current entry.
    // Also prune the current entry if we are to replace the current entry.
    // last_committed_entry_index_ must be updated here since calls to
    // NotifyPrunedEntries() below may re-enter and we must make sure
    // last_committed_entry_index_ is not left in an invalid state.
    if (replace)
      --last_committed_entry_index_;

    int num_pruned = 0;
    while (last_committed_entry_index_ < (current_size - 1)) {
      num_pruned++;
      entries_.pop_back();
      current_size--;
    }
    if (num_pruned > 0)  // Only notify if we did prune something.
      NotifyPrunedEntries(this, false, num_pruned);
  }

  PruneOldestEntryIfFull();

  entries_.push_back(linked_ptr<NavigationEntryImpl>(entry));
  last_committed_entry_index_ = static_cast<int>(entries_.size()) - 1;

  // This is a new page ID, so we need everybody to know about it.
  delegate_->UpdateMaxPageID(entry->GetPageID());
}

void NavigationControllerImpl::PruneOldestEntryIfFull() {
  if (entries_.size() >= max_entry_count()) {
    DCHECK_EQ(max_entry_count(), entries_.size());
    DCHECK_GT(last_committed_entry_index_, 0);
    RemoveEntryAtIndex(0);
    NotifyPrunedEntries(this, true, 1);
  }
}

void NavigationControllerImpl::NavigateToPendingEntry(ReloadType reload_type) {
  needs_reload_ = false;

  // If we were navigating to a slow-to-commit page, and the user performs
  // a session history navigation to the last committed page, RenderViewHost
  // will force the throbber to start, but WebKit will essentially ignore the
  // navigation, and won't send a message to stop the throbber. To prevent this
  // from happening, we drop the navigation here and stop the slow-to-commit
  // page from loading (which would normally happen during the navigation).
  if (pending_entry_index_ != -1 &&
      pending_entry_index_ == last_committed_entry_index_ &&
      (entries_[pending_entry_index_]->restore_type() ==
          NavigationEntryImpl::RESTORE_NONE) &&
      (entries_[pending_entry_index_]->GetTransitionType() &
          PAGE_TRANSITION_FORWARD_BACK)) {
    delegate_->Stop();

    // If an interstitial page is showing, we want to close it to get back
    // to what was showing before.
    if (delegate_->GetInterstitialPage())
      delegate_->GetInterstitialPage()->DontProceed();

    DiscardNonCommittedEntries();
    return;
  }

  // If an interstitial page is showing, the previous renderer is blocked and
  // cannot make new requests.  Unblock (and disable) it to allow this
  // navigation to succeed.  The interstitial will stay visible until the
  // resulting DidNavigate.
  if (delegate_->GetInterstitialPage()) {
    static_cast<InterstitialPageImpl*>(delegate_->GetInterstitialPage())->
        CancelForNavigation();
  }

  // For session history navigations only the pending_entry_index_ is set.
  if (!pending_entry_) {
    DCHECK_NE(pending_entry_index_, -1);
    pending_entry_ = entries_[pending_entry_index_].get();
  }

  // This call does not support re-entrancy.  See http://crbug.com/347742.
  CHECK(!in_navigate_to_pending_entry_);
  in_navigate_to_pending_entry_ = true;
  bool success = delegate_->NavigateToPendingEntry(reload_type);
  in_navigate_to_pending_entry_ = false;

  if (!success)
    DiscardNonCommittedEntries();

  // If the entry is being restored and doesn't have a SiteInstance yet, fill
  // it in now that we know. This allows us to find the entry when it commits.
  if (pending_entry_ && !pending_entry_->site_instance() &&
      pending_entry_->restore_type() != NavigationEntryImpl::RESTORE_NONE) {
    pending_entry_->set_site_instance(static_cast<SiteInstanceImpl*>(
        delegate_->GetPendingSiteInstance()));
    pending_entry_->set_restore_type(NavigationEntryImpl::RESTORE_NONE);
  }
}

void NavigationControllerImpl::NotifyNavigationEntryCommitted(
    LoadCommittedDetails* details) {
  details->entry = GetLastCommittedEntry();

  // We need to notify the ssl_manager_ before the web_contents_ so the
  // location bar will have up-to-date information about the security style
  // when it wants to draw.  See http://crbug.com/11157
  ssl_manager_.DidCommitProvisionalLoad(*details);

  delegate_->NotifyNavigationStateChanged(kInvalidateAll);
  delegate_->NotifyNavigationEntryCommitted(*details);

  // TODO(avi): Remove. http://crbug.com/170921
  NotificationDetails notification_details =
      Details<LoadCommittedDetails>(details);
  NotificationService::current()->Notify(
      NOTIFICATION_NAV_ENTRY_COMMITTED,
      Source<NavigationController>(this),
      notification_details);
}

// static
size_t NavigationControllerImpl::max_entry_count() {
  if (max_entry_count_for_testing_ != kMaxEntryCountForTestingNotSet)
     return max_entry_count_for_testing_;
  return kMaxSessionHistoryEntries;
}

void NavigationControllerImpl::SetActive(bool is_active) {
  if (is_active && needs_reload_)
    LoadIfNecessary();
}

void NavigationControllerImpl::LoadIfNecessary() {
  if (!needs_reload_)
    return;

  // Calling Reload() results in ignoring state, and not loading.
  // Explicitly use NavigateToPendingEntry so that the renderer uses the
  // cached state.
  pending_entry_index_ = last_committed_entry_index_;
  NavigateToPendingEntry(NO_RELOAD);
}

void NavigationControllerImpl::NotifyEntryChanged(const NavigationEntry* entry,
                                                  int index) {
  EntryChangedDetails det;
  det.changed_entry = entry;
  det.index = index;
  NotificationService::current()->Notify(
      NOTIFICATION_NAV_ENTRY_CHANGED,
      Source<NavigationController>(this),
      Details<EntryChangedDetails>(&det));
}

void NavigationControllerImpl::FinishRestore(int selected_index,
                                             RestoreType type) {
  DCHECK(selected_index >= 0 && selected_index < GetEntryCount());
  ConfigureEntriesForRestore(&entries_, type);

  SetMaxRestoredPageID(static_cast<int32>(GetEntryCount()));

  last_committed_entry_index_ = selected_index;
}

void NavigationControllerImpl::DiscardNonCommittedEntriesInternal() {
  DiscardPendingEntry();
  DiscardTransientEntry();
}

void NavigationControllerImpl::DiscardPendingEntry() {
  // It is not safe to call DiscardPendingEntry while NavigateToEntry is in
  // progress, since this will cause a use-after-free.  http://crbug.com/347742.
  CHECK(!in_navigate_to_pending_entry_);

  if (pending_entry_index_ == -1)
    delete pending_entry_;
  pending_entry_ = NULL;
  pending_entry_index_ = -1;
}

void NavigationControllerImpl::DiscardTransientEntry() {
  if (transient_entry_index_ == -1)
    return;
  entries_.erase(entries_.begin() + transient_entry_index_);
  if (last_committed_entry_index_ > transient_entry_index_)
    last_committed_entry_index_--;
  transient_entry_index_ = -1;
}

int NavigationControllerImpl::GetEntryIndexWithPageID(
    SiteInstance* instance, int32 page_id) const {
  for (int i = static_cast<int>(entries_.size()) - 1; i >= 0; --i) {
    if ((entries_[i]->site_instance() == instance) &&
        (entries_[i]->GetPageID() == page_id))
      return i;
  }
  return -1;
}

NavigationEntry* NavigationControllerImpl::GetTransientEntry() const {
  if (transient_entry_index_ == -1)
    return NULL;
  return entries_[transient_entry_index_].get();
}

void NavigationControllerImpl::SetTransientEntry(NavigationEntry* entry) {
  // Discard any current transient entry, we can only have one at a time.
  int index = 0;
  if (last_committed_entry_index_ != -1)
    index = last_committed_entry_index_ + 1;
  DiscardTransientEntry();
  entries_.insert(
      entries_.begin() + index, linked_ptr<NavigationEntryImpl>(
          NavigationEntryImpl::FromNavigationEntry(entry)));
  transient_entry_index_ = index;
  delegate_->NotifyNavigationStateChanged(kInvalidateAll);
}

void NavigationControllerImpl::InsertEntriesFrom(
    const NavigationControllerImpl& source,
    int max_index) {
  DCHECK_LE(max_index, source.GetEntryCount());
  size_t insert_index = 0;
  for (int i = 0; i < max_index; i++) {
    // When cloning a tab, copy all entries except interstitial pages
    if (source.entries_[i].get()->GetPageType() !=
        PAGE_TYPE_INTERSTITIAL) {
      entries_.insert(entries_.begin() + insert_index++,
                      linked_ptr<NavigationEntryImpl>(
                          new NavigationEntryImpl(*source.entries_[i])));
    }
  }
}

void NavigationControllerImpl::SetGetTimestampCallbackForTest(
    const base::Callback<base::Time()>& get_timestamp_callback) {
  get_timestamp_callback_ = get_timestamp_callback;
}

}  // namespace content
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root/content/browser/frame_host/navigation_controller_impl.cc

DEFINITIONS
