android: add Java-side support for browser compositor async readback

content/public/browser/android/compositor.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 #define CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_
 
 #include "base/callback.h"
 #include "cc/resources/ui_resource_bitmap.h"
 #include "cc/resources/ui_resource_client.h"
@@ skipping 46 matching lines @@
   // Set the output surface handle which the compositor renders into.
   // DEPRECATED: Use SetSurface() which takes a Java Surface object.
   virtual void SetWindowSurface(ANativeWindow* window) = 0;
 
   // Set the output surface which the compositor renders into.
   virtual void SetSurface(jobject surface) = 0;
 
   // Tells the view tree to assume a transparent background when rendering.
   virtual void SetHasTransparentBackground(bool flag) = 0;
 
-  // Attempts to composite and read back the result into the provided buffer.
-  // The buffer must be at least window width * height * 4 (RGBA) bytes large.
-  // The buffer is not modified if false is returned.
-  virtual bool CompositeAndReadback(void *pixels, const gfx::Rect& rect) = 0;
-
   // Request layout and draw. You only need to call this if you need to trigger
   // Composite *without* having modified the layer tree.
   virtual void SetNeedsComposite() = 0;
 
   // Generates a UIResource and returns a UIResourceId.  |is_transient|
   // indicates whether or not to release the resource once the bitmap
   // has been uploaded. May return 0.
   virtual cc::UIResourceId GenerateUIResource(const SkBitmap& bitmap,
                                               bool is_transient) = 0;
 
   // Generates an ETC1 compressed UIResource.  See above for |is_transient|.
   // May return 0.
   virtual cc::UIResourceId GenerateCompressedUIResource(const gfx::Size& size,
                                                         void* pixels,
                                                         bool is_transient) = 0;
 
   // Deletes a UIResource.
   virtual void DeleteUIResource(cc::UIResourceId resource_id) = 0;
 
  protected:
   Compositor() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ANDROID_COMPOSITOR_H_