Implement transform/clip support for Android WebView.

cc/output/output_surface_client.h

Index: cc/output/output_surface_client.h
diff --git a/cc/output/output_surface_client.h b/cc/output/output_surface_client.h
index 1f188afe8fac3a3928069ebcda7e5e7c2e126603..79de52a6ecb57f9bbc2dec1d333b4d856134143c 100644
--- a/cc/output/output_surface_client.h
+++ b/cc/output/output_surface_client.h
@@ -9,6 +9,10 @@
 #include "cc/base/cc_export.h"
 #include "ui/gfx/rect.h"
 
+namespace gfx {
+class Transform;
+}
+
 namespace cc {
 
 class CompositorFrameAck;
@@ -22,6 +26,8 @@ class CC_EXPORT OutputSurfaceClient {
   virtual void OnSendFrameToParentCompositorAck(const CompositorFrameAck&) = 0;
   virtual void OnSwapBuffersComplete() = 0;
   virtual void DidLoseOutputSurface() = 0;
+  virtual void SetExternalDrawConstraints(const gfx::Transform& transform,
+                                          gfx::Rect viewport) = 0;
 
  protected:
   virtual ~OutputSurfaceClient() {}