Re-land: Make 2D canvas smarter about chosing whether or not to use GPU acceleration

third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h

Index: third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
diff --git a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
index fe94e77c5fa886895fc6d84eb6ab6d76da4d2fe1..a670d65bc08ab24726bcd5979cca39b32e78e022 100644
--- a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
+++ b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
@@ -53,7 +53,13 @@ class SharedContextRateLimiter;
 class PLATFORM_EXPORT Canvas2DLayerBridge : public WebExternalTextureLayerClient, public WebThread::TaskObserver, public RefCounted<Canvas2DLayerBridge> {
     WTF_MAKE_NONCOPYABLE(Canvas2DLayerBridge);
 public:
-    static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, OpacityMode, int msaaSampleCount);
+    enum AccelerationMode {
+        DisableAcceleration,
+        EnableAcceleration,
+        ForceAccelerationForTesting,
+    };
+
+    static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
 
     ~Canvas2DLayerBridge() override;
 
@@ -71,7 +77,7 @@ public:
     bool checkSurfaceValid();
     bool restoreSurface();
     WebLayer* layer() const;
-    bool isAccelerated() const { return true; }
+    bool isAccelerated() const;
     void setFilterQuality(SkFilterQuality);
     void setIsHidden(bool);
     void setImageBuffer(ImageBuffer*);
@@ -79,14 +85,15 @@ public:
     bool writePixels(const SkImageInfo&, const void* pixels, size_t rowBytes, int x, int y);
     void flush();
     void flushGpu();
+    void prepareSurfaceForPaintingIfNeeded();
     bool isHidden() { return m_isHidden; }
 
     void beginDestruction();
 
-    PassRefPtr<SkImage> newImageSnapshot();
+    PassRefPtr<SkImage> newImageSnapshot(AccelerationHint);
 
 private:
-    Canvas2DLayerBridge(PassOwnPtr<WebGraphicsContext3DProvider>, PassRefPtr<SkSurface>, int, OpacityMode);
+    Canvas2DLayerBridge(PassOwnPtr<WebGraphicsContext3DProvider>, const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
     WebGraphicsContext3D* context();
     void startRecording();
     void skipQueuedDrawCommands();
@@ -97,6 +104,9 @@ private:
     void willProcessTask() override;
     void didProcessTask() override;
 
+    SkSurface* getOrCreateSurface(AccelerationHint = PreferAcceleration);
+    bool shouldAccelerate(AccelerationHint) const;
+
     OwnPtr<SkPictureRecorder> m_recorder;
     RefPtr<SkSurface> m_surface;
     int m_initialSurfaceSaveCount;
@@ -135,6 +145,7 @@ private:
 
     Deque<MailboxInfo, MaxActiveMailboxes> m_mailboxes;
     GLenum m_lastFilter;
+    AccelerationMode m_accelerationMode;
     OpacityMode m_opacityMode;
     IntSize m_size;
     int m_recordingPixelCount;