Implementing promise-based commit for driving OffscreenCanvas animations

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

Index: third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcher.h
diff --git a/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcher.h b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcher.h
index 60f7005f4ef093f5637a58d7b8a58c0f66b2cdde..d5b7885e19d36d59872d6142959e24e2470f19e0 100644
--- a/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcher.h
+++ b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcher.h
@@ -6,6 +6,7 @@
 #define OffscreenCanvasFrameDispatcher_h
 
 #include "platform/PlatformExport.h"
+#include "platform/WebTaskRunner.h"
 #include "wtf/RefPtr.h"
 #include "wtf/WeakPtr.h"
 
@@ -13,13 +14,17 @@ namespace blink {
 
 class StaticBitmapImage;
 
+class OffscreenCanvasFrameDispatcherClient {

[xlai (Olivia), 2016/12/21 19:54:25]

Just a suggestion: I see that the relationship of this new class to
OffscreenCanvasFrameDispatcher is similar to that
CanvasSurfaceLayerBridgeObserver to CanvasSurfaceLayerBridge. Do you think it's
better to rename "*Client" to "*Observer" for consistency or symmetry between
html canvas side and offscreencanvas side? 

[Justin Novosad, 2016/12/21 21:15:40]

We use both in blink. It is really just a matter of semantics.  The term
"Observer" implies that the object is watching another other (subscribing to
change notifications). The term "Client" implies that the object is being served
something (event signals, for example) by another object.  The difference is
subtle and it is the same code pattern. 

IMHO, both classes are aptly named as is.

+ public:
+  virtual void beginFrame() = 0;
+};
+
 class PLATFORM_EXPORT OffscreenCanvasFrameDispatcher {
  public:
-  OffscreenCanvasFrameDispatcher() : m_weakPtrFactory(this) {}
   virtual ~OffscreenCanvasFrameDispatcher() {}
   virtual void dispatchFrame(RefPtr<StaticBitmapImage>,
                              double commitStartTime,
-                             bool isWebGLSoftwareRendering = false) = 0;
+                             bool isWebGLSoftwareRendering) = 0;
   virtual void reclaimResource(unsigned resourceId) = 0;
 
   virtual void reshape(int width, int height) = 0;
@@ -28,8 +33,15 @@ class PLATFORM_EXPORT OffscreenCanvasFrameDispatcher {
     return m_weakPtrFactory.createWeakPtr();
   }
 
+  OffscreenCanvasFrameDispatcherClient* client() { return m_client; }
+
+ protected:
+  OffscreenCanvasFrameDispatcher(OffscreenCanvasFrameDispatcherClient* client)
+      : m_weakPtrFactory(this), m_client(client) {}
+
  private:
   WeakPtrFactory<OffscreenCanvasFrameDispatcher> m_weakPtrFactory;
+  OffscreenCanvasFrameDispatcherClient* m_client;
 };
 
 }  // namespace blink