IsValidFrame      214 src/frames.cc    if (!done() && !IsValidFrame()) Advance();
IsValidFrame      220 src/frames.cc    if (!done() && !IsValidFrame()) Advance();
IsValidFrame      228 src/frames.cc      if (IsValidFrame()) return;
IsValidFrame      304 src/frames.cc    iteration_done_ = !IsValidFrame(last_frame) ||
IsValidFrame      789 src/frames.h     bool IsValidFrame();
IsValidFrame      844 src/frames.h     bool IsValidFrame(StackFrame* frame) const;