InvalidMailboxIndex   99 Source/platform/graphics/Canvas2DLayerBridge.cpp     , m_releasedMailboxInfoIndex(InvalidMailboxIndex)
InvalidMailboxIndex  295 Source/platform/graphics/Canvas2DLayerBridge.cpp     return m_releasedMailboxInfoIndex != InvalidMailboxIndex;
InvalidMailboxIndex  319 Source/platform/graphics/Canvas2DLayerBridge.cpp     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
InvalidMailboxIndex  357 Source/platform/graphics/Canvas2DLayerBridge.cpp     m_releasedMailboxInfoIndex = InvalidMailboxIndex;