Send array of paint rects and bitmaps as opposed to a Union

chrome/renderer/render_widget.h

 // Copyright (c) 2009 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_RENDERER_RENDER_WIDGET_H_
 #define CHROME_RENDERER_RENDER_WIDGET_H_
 
 #include <vector>
 #include "base/basictypes.h"
 #include "base/gfx/native_widget_types.h"
@@ skipping 98 matching lines @@
   // Initializes this view with the given opener.  CompleteInit must be called
   // later.
   void Init(int32 opener_id);
 
   // Finishes creation of a pending view started with Init.
   void CompleteInit(gfx::NativeViewId parent);
 
   // Paints the given rectangular region of the WebWidget into canvas (a
   // shared memory segment returned by AllocPaintBuf on Windows). The caller
   // must ensure that the given rect fits within the bounds of the WebWidget.
+  void PaintThisRect(const gfx::Rect& rect, skia::PlatformCanvas* canvas);
   void PaintRect(const gfx::Rect& rect, skia::PlatformCanvas* canvas);
+  void PaintRects(const std::vector<gfx::Rect>& rect,
+                  skia::PlatformCanvas* canvas);
 
   void DoDeferredPaint();
   void DoDeferredScroll();
   void DoDeferredClose();
   void DoDeferredSetWindowRect(const WebKit::WebRect& pos);
 
   // This method is called immediately after PaintRect but before the
   // corresponding paint or scroll message is send to the widget host.
   virtual void DidPaint() {}
 
@@ skipping 88 matching lines @@
   // The size of the RenderWidget.
   gfx::Size size_;
 
   // Transport DIBs that are currently in use to transfer an image to the
   // browser.
   TransportDIB* current_paint_buf_;
   TransportDIB* current_scroll_buf_;
 
   // The smallest bounding rectangle that needs to be re-painted.  This is non-
   // empty if a paint event is pending.
-  gfx::Rect paint_rect_;
+  std::vector<gfx::Rect> paint_rects_;
 
   // The clip rect for the pending scroll event.  This is non-empty if a
   // scroll event is pending.
   gfx::Rect scroll_rect_;
 
   // The area that must be reserved for drawing the resize corner.
   gfx::Rect resizer_rect_;
 
   // The scroll delta for a pending scroll event.
   gfx::Point scroll_delta_;
@@ skipping 55 matching lines @@
 
   // While we are waiting for the browser to update window sizes,
   // we track the pending size temporarily.
   int pending_window_rect_count_;
   WebKit::WebRect pending_window_rect_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 #endif  // CHROME_RENDERER_RENDER_WIDGET_H_