Transfer canvas state to the next frame with noticable restrictions.

Source/platform/graphics/RecordingImageBufferSurface.h

Index: Source/platform/graphics/RecordingImageBufferSurface.h
diff --git a/Source/platform/graphics/RecordingImageBufferSurface.h b/Source/platform/graphics/RecordingImageBufferSurface.h
index c8af6a045081ddfc38190d3bd03f27eb84842e20..f3e52b060c87a403755180d9f7193e29c63bcb1b 100644
--- a/Source/platform/graphics/RecordingImageBufferSurface.h
+++ b/Source/platform/graphics/RecordingImageBufferSurface.h
@@ -7,6 +7,7 @@
 
 #include "platform/graphics/ImageBufferSurface.h"
 #include "public/platform/WebThread.h"
+#include "third_party/skia/include/core/SkDeque.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/RefPtr.h"
 
@@ -39,12 +40,21 @@ private:
     void initializeCurrentFrame();
     bool finalizeFrameInternal();
 
+    // saves current clip and transform matrix of canvas
+    bool saveState(SkCanvas*);
+    // we should make sure that we can transfer state in saveState
+    void setCurrentState(SkCanvas*);
+
     OwnPtr<SkPictureRecorder> m_currentFrame;
     RefPtr<SkPicture> m_previousFrame;
     OwnPtr<SkCanvas> m_rasterCanvas;
     ImageBuffer* m_imageBuffer;
     int m_initialSaveCount;
     bool m_frameWasCleared;
+
+    struct StateRec;

[Justin Novosad, 2014/08/26 16:57:20]

This does not need to be forward declared since it is not referenced in the
header.

[Sergey, 2014/08/28 09:55:34]

Actually, the intention was to make it inner class of
RecordingImageBufferSurface. Ok, removed.

+    SkDeque m_stateStack;

[Justin Novosad, 2014/08/26 16:57:20]

This does not need to be a member of RecordingImageBufferSurface. It should be a
local variable in finalizeFrame().  Also, you should use a Blink class here
(WTF::Deque?)

[Sergey, 2014/08/28 09:55:34]

Done.

+    uint32_t m_stateStackStorage[32];

[Justin Novosad, 2014/08/26 16:57:20]

After you move this into the cpp. The 32 should be in a constant and you you add
a comment to explain why 32 is a reasonable value.

[Sergey, 2014/08/28 09:55:34]

Done.

 };
 
 } // namespace blink