Optimize the rendering when there are pending key events....

chrome/browser/renderer_host/render_widget_host.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_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_H_
 
 #include <deque>
 
 #include "app/gfx/native_widget_types.h"
@@ skipping 429 matching lines @@
 
   // Scrolls the given |clip_rect| in the backing by the given dx/dy amount. The
   // |dib| and its corresponding location |bitmap_rect| in the backing store
   // is the newly painted pixels by the renderer.
   void ScrollBackingStoreRect(TransportDIB* dib,
                               const gfx::Rect& bitmap_rect,
                               int dx, int dy,
                               const gfx::Rect& clip_rect,
                               const gfx::Size& view_size);
 
+  // Called by OnMsgInputEventAck() to process a keyboard event ack message.
+  void ProcessKeyboardEventAck(int type, bool processed);
+
   // The View associated with the RenderViewHost. The lifetime of this object
   // is associated with the lifetime of the Render process. If the Renderer
   // crashes, its View is destroyed and this pointer becomes NULL, even though
   // render_view_host_ lives on to load another URL (creating a new View while
   // doing so).
   RenderWidgetHostView* view_;
 
   // Created during construction but initialized during Init*(). Therefore, it
   // is guaranteed never to be NULL, but its channel may be NULL if the
   // renderer crashed, so you must always check that.
@@ skipping 110 matching lines @@
   // shall not send the following sequence of Char events, which was generated
   // by this RawKeyDown event, to the renderer. Otherwise the renderer may
   // handle the Char events and cause unexpected behavior.
   // For example, pressing alt-2 may let the browser switch to the second tab,
   // but the Char event generated by alt-2 may also activate a HTML element
   // if its accesskey happens to be "2", then the user may get confused when
   // switching back to the original tab, because the content may already be
   // changed.
   bool suppress_next_char_events_;
 
+  // True if the PaintRect_ACK message for the last PaintRect message is still
+  // not sent yet. This is used for optimizing the painting overhead when there
+  // are many pending key events in the queue.
+  bool paint_ack_postponed_;
+
+  // The time when a PaintRect_ACK message is postponed, so that we can send the
+  // message after a certain duration.
+  base::TimeTicks paint_ack_postponed_time_;
+
   // During the call to some methods, eg. OnMsgInputEventAck, this
   // RenderWidgetHost object may be destroyed before executing some code that
   // still want to access this object. To avoid this situation, |death_flag_|
   // shall be pointed to a local variable in the method, and then |*death_flag_|
   // will be set to true when destroying this RenderWidgetHost object, then the
   // method shall exit immediately when |*death_flag_| becomes true.
   bool* death_flag_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHost);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_H_