Android:Allow a read-back request to wait for a first frame

content/browser/renderer_host/render_widget_host_view_android.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_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_ANDROID_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_ANDROID_H_
 
 #include <map>
 #include <queue>
 
@@ skipping 40 matching lines @@
 }
 
 namespace content {
 class ContentViewCoreImpl;
 class OverscrollGlow;
 class RenderWidgetHost;
 class RenderWidgetHostImpl;
 struct DidOverscrollParams;
 struct NativeWebKeyboardEvent;
 
+class ReadbackRequest {
+ public:
+  explicit ReadbackRequest(
+      float scale,
+      SkColorType color_type,
+      gfx::Rect src_subrect,
+      const base::Callback<void(bool, const SkBitmap&)>& result_callback)
+      : scale_(scale),
+        color_type_(color_type),
+        src_subrect_(src_subrect),
+        result_callback_(result_callback) {}
+  ~ReadbackRequest() {};
+  float GetScale() { return scale_; }
+  SkColorType GetColorFormat() { return color_type_; }
+  gfx::Rect GetCaptureRect() { return src_subrect_; }

[no sievers, 2014/07/28 17:07:06]

nit: return a reference for the rect

+  const base::Callback<void(bool, const SkBitmap&)>& GetResultCallback() {
+    return result_callback_;
+  }
+
+ private:
+  ReadbackRequest() {};
+  float scale_;
+  SkColorType color_type_;
+  gfx::Rect src_subrect_;
+  base::Callback<void(bool, const SkBitmap&)> result_callback_;
+};
+
 // -----------------------------------------------------------------------------
 // See comments in render_widget_host_view.h about this class and its members.
 // -----------------------------------------------------------------------------
 class CONTENT_EXPORT RenderWidgetHostViewAndroid
     : public RenderWidgetHostViewBase,
       public cc::DelegatedFrameResourceCollectionClient,
       public ImageTransportFactoryAndroidObserver,
       public ui::GestureProviderClient,
       public ui::WindowAndroidObserver,
       public DelegatedFrameEvictorClient,
@@ skipping 237 matching lines @@
   void InternalSwapCompositorFrame(uint32 output_surface_id,
                                    scoped_ptr<cc::CompositorFrame> frame);
 
   bool Animate(base::TimeTicks frame_time);
 
   void OnContentScrollingChange();
   bool IsContentScrolling() const;
 
   float GetDpiScale() const;
 
+  // Add the ReadbackRequest to the queue and wait for frame arraival.

[no sievers, 2014/07/28 17:07:06]

not: typo in 'arraival'

+  void WaitForValidFrameArrival(const ReadbackRequest& readback_request);

[no sievers, 2014/07/28 17:07:06]

nit: How about a more specific name? Something like 'DeferReadback' or so.

+
+  // Handles all unprocessed and pending readback requests.
+  void ProcessPendingReadbackRequests();
+
   // The model object.
   RenderWidgetHostImpl* host_;
 
   // Used to track whether this render widget needs a BeginFrame.
   bool needs_begin_frame_;
 
   bool is_showing_;
 
   // ContentViewCoreImpl is our interface to the view system.
   ContentViewCoreImpl* content_view_core_;
@@ skipping 60 matching lines @@
                   scoped_ptr<cc::CompositorFrame> output_frame);
     ~LastFrameInfo();
     uint32 output_surface_id;
     scoped_ptr<cc::CompositorFrame> frame;
   };
 
   scoped_ptr<LastFrameInfo> last_frame_info_;
 
   TextSurroundingSelectionCallback text_surrounding_selection_callback_;
 
+  // List of readbackrequests waiting for arrival of a valid frame.
+  std::queue<ReadbackRequest> readbacks_waiting_for_frame_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAndroid);
 };
 
 } // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_ANDROID_H_