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

chrome/browser/renderer_host/backing_store.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_BACKING_STORE_H_
 #define CHROME_BROWSER_RENDERER_HOST_BACKING_STORE_H_
 
 #include "base/basictypes.h"
 #include "base/gfx/rect.h"
 #include "base/gfx/size.h"
@@ skipping 80 matching lines @@
 #endif
 
   // Paints the bitmap from the renderer onto the backing store.  bitmap_rect
   // gives the location of bitmap, and copy_rect specifies the subregion of
   // the backingstore to be painted from the bitmap.
   void PaintRect(base::ProcessHandle process,
                  TransportDIB* bitmap,
                  const gfx::Rect& bitmap_rect,
                  const gfx::Rect& copy_rect);
 
-  // Scrolls the given rect in the backing store, replacing the given region
-  // identified by |bitmap_rect| by the bitmap in the file identified by the
-  // given file handle.
-  void ScrollRect(base::ProcessHandle process,
-                  TransportDIB* bitmap, const gfx::Rect& bitmap_rect,
-                  int dx, int dy,
+  // Scrolls the contents of clip_rect in the backing store by dx or dy (but dx
+  // and dy cannot both be non-zero).
+  void ScrollRect(int dx, int dy,
                   const gfx::Rect& clip_rect,
                   const gfx::Size& view_size);
 
  private:
 #if defined(OS_MACOSX)
   // Creates a CGLayer associated with its owner view's window's graphics
   // context, sized properly for the backing store.  Returns NULL if the owner
   // is not in a window with a CGContext.  cg_layer_ is assigned this method's
   // result.
   CGLayerRef CreateCGLayer();
@@ skipping 49 matching lines @@
   // This is the RENDER picture pointing at |pixmap_|.
   XID picture_;
   // This is a default graphic context, used in XCopyArea
   void* pixmap_gc_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(BackingStore);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_BACKING_STORE_H_