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

chrome/browser/renderer_host/backing_store_mac.mm

Index: chrome/browser/renderer_host/backing_store_mac.mm
===================================================================
--- chrome/browser/renderer_host/backing_store_mac.mm	(revision 34937)
+++ chrome/browser/renderer_host/backing_store_mac.mm	(working copy)
@@ -99,10 +99,7 @@
 }
 
 // Scroll the contents of our CGLayer
-void BackingStore::ScrollRect(base::ProcessHandle process,
-                              TransportDIB* bitmap,
-                              const gfx::Rect& bitmap_rect,
-                              int dx, int dy,
+void BackingStore::ScrollRect(int dx, int dy,
                               const gfx::Rect& clip_rect,
                               const gfx::Size& view_size) {
   DCHECK_NE(static_cast<bool>(cg_layer()), static_cast<bool>(cg_bitmap()));
@@ -158,9 +155,6 @@
       cg_bitmap_.swap(new_bitmap);
     }
   }
-  // Now paint the new bitmap data
-  PaintRect(process, bitmap, bitmap_rect, bitmap_rect);
-  return;
 }
 
 CGLayerRef BackingStore::CreateCGLayer() {