Combine ViewHostMsg_{Paint,Scroll}Rect into one IPC....

chrome/browser/renderer_host/render_widget_host_view.h

 // Copyright (c) 2006-2008 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 CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_H_
 
 #include "app/gfx/native_widget_types.h"
 #include "base/shared_memory.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ skipping 92 matching lines @@
   // a paint ack after this returns, so if the view only ever invalidates in
   // response to this, then on Windows, where WM_PAINT has lower priority than
   // events which can cause renderer resizes/paint rect updates, e.g.
   // drag-resizing can starve painting; this function thus provides the view its
   // main chance to ensure it stays painted and not just invalidated.  On the
   // other hand, if this always blindly paints, then if we're already in the
   // midst of a paint on the callstack, we can double-paint unnecessarily.
   // (Worse, we might recursively call RenderWidgetHost::GetBackingStore().)
   // Thus implementers should generally paint as much of |rect| as possible
   // synchronously with as little overpainting as possible.
-  virtual void DidPaintRect(const gfx::Rect& rect) = 0;
+  virtual void DidPaintBackingStoreRects(
+      const std::vector<gfx::Rect>& rects) = 0;
 
   // Informs the view that a portion of the widget's backing store was scrolled
   // by dx pixels horizontally and dy pixels vertically. The view should copy
   // the exposed pixels from the backing store of the render widget (which has
   // already been scrolled) onto the screen.
-  virtual void DidScrollRect(
+  virtual void DidScrollBackingStoreRect(
       const gfx::Rect& rect, int dx, int dy) = 0;
 
   // Notifies the View that the renderer has ceased to exist.
   virtual void RenderViewGone() = 0;
 
   // Notifies the View that the renderer will be delete soon.
   virtual void WillDestroyRenderWidget(RenderWidgetHost* rwh) = 0;
 
   // Tells the View to destroy itself.
   virtual void Destroy() = 0;
@@ skipping 56 matching lines @@
 
   // A custom background to paint behind the web content. This will be tiled
   // horizontally. Can be null, in which case we fall back to painting white.
   SkBitmap background_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostView);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_H_