Don't use PostTask queueing between compositor and main thread.

content/browser/renderer_host/input/input_router_impl.h

 // Copyright 2013 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_BROWSER_RENDERER_HOST_INPUT_INPUT_ROUTER_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_ROUTER_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 195 matching lines @@
   int frame_tree_node_id_;
 
   // (Similar to |mouse_move_pending_|.) True while waiting for SelectRange_ACK
   // or MoveRangeSelectionExtent_ACK.
   bool select_message_pending_;
 
   // Queue of pending select messages to send after receving the next select
   // message ack.
   std::deque<IPC::Message*> pending_select_messages_;
 
-  // (Similar to |mouse_move_pending_|.) True while waiting for MoveCaret_ACK.
+  // True while waiting for MoveCaret_ACK.
   bool move_caret_pending_;
 
-  // (Similar to |next_mouse_move_|.) The next MoveCaret to send, if any.
+  // The next MoveCaret to send, if any.
   std::unique_ptr<IPC::Message> next_move_caret_;
 
-  // True if a mouse move event was sent to the render view and we are waiting
-  // for a corresponding InputHostMsg_HandleInputEvent_ACK message.
-  bool mouse_move_pending_;
-
-  // The next mouse move event to send (only non-null while mouse_move_pending_
-  // is true).
-  std::unique_ptr<MouseEventWithLatencyInfo> next_mouse_move_;
-  MouseEventWithLatencyInfo current_mouse_move_;
+  // A queue of the mouse move events sent to the renderer. Similar
+  // to |key_queue_|.
+  typedef std::deque<MouseEventWithLatencyInfo> MouseMoveQueue;
+  MouseMoveQueue mouse_move_queue_;
 
   // A queue of keyboard events. We can't trust data from the renderer so we
   // stuff key events into a queue and pop them out on ACK, feeding our copy
   // back to whatever unhandled handler instead of the returned version.
   typedef std::deque<NativeWebKeyboardEventWithLatencyInfo> KeyQueue;
   KeyQueue key_queue_;
 
   // The time when an input event was sent to the client.
   base::TimeTicks input_event_start_time_;
 
@@ skipping 22 matching lines @@
   InputEventStreamValidator output_stream_validator_;
 
   float device_scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(InputRouterImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_ROUTER_IMPL_H_