Disable partial swaps for webview guest renderer until we can figure out how to do that properly.

content/renderer/render_widget.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_RENDERER_RENDER_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 
 #include <deque>
 #include <map>
 
@@ skipping 509 matching lines @@
   bool update_reply_pending_;
 
   // True if we need to send an UpdateRect message to notify the browser about
   // an already-completed auto-resize.
   bool need_update_rect_for_auto_resize_;
 
   // True if the underlying graphics context supports asynchronous swap.
   // Cached on the RenderWidget because determining support is costly.
   bool using_asynchronous_swapbuffers_;
 
+  // Specifies whether partially swapping composited buffers is
+  // allowed for a renderer. Partial swaps will be used if they are both
+  // allowed and supported.
+  bool allow_partial_swap_;
+
   // Number of OnSwapBuffersComplete we are expecting. Incremented each time
   // WebWidget::composite has been been performed when the RenderWidget subclass
   // SupportsAsynchronousSwapBuffers. Decremented in OnSwapBuffers. Will block
   // rendering.
   int num_swapbuffers_complete_pending_;
 
   // When accelerated rendering is on, is the maximum number of swapbuffers that
   // can be outstanding before we start throttling based on
   // OnSwapBuffersComplete callback.
   static const int kMaxSwapBuffersPending = 2;
@@ skipping 121 matching lines @@
 
   // Specified whether the compositor will run in its own thread.
   bool is_threaded_compositing_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_