input: Immediately start timer for synthetic event dispatch.

content/browser/renderer_host/input/synthetic_gesture_controller.cc

 // 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.
 
 #include "content/browser/renderer_host/input/synthetic_gesture_controller.h"
 
 #include <utility>
 
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 22 matching lines @@
 
   bool was_empty = pending_gesture_queue_.IsEmpty();
 
   pending_gesture_queue_.Push(std::move(synthetic_gesture),
                               completion_callback);
 
   if (was_empty)
     StartGesture(*pending_gesture_queue_.FrontGesture());
 }
 
-void SyntheticGestureController::RequestBeginFrame() {
-  DCHECK(!dispatch_timer_.IsRunning());
-  delegate_->RequestBeginFrameForSynthesizedInput(
-      base::BindOnce(&SyntheticGestureController::OnBeginFrame,
-                     weak_ptr_factory_.GetWeakPtr()));
-}
-
-void SyntheticGestureController::OnBeginFrame() {
-  // In order to make sure we get consistent results across runs, we attempt to
-  // start the timer at a fixed offset from the vsync. Starting the timer
-  // shortly after a begin-frame is likely to produce latency close to the worst
-  // cases. We feel 2 milliseconds is a good offset for this.
-  constexpr base::TimeDelta kSynthesizedDispatchDelay =
-      base::TimeDelta::FromMilliseconds(2);
-  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-      FROM_HERE,
-      base::BindOnce(&SyntheticGestureController::StartTimer,
-                     weak_ptr_factory_.GetWeakPtr()),
-      kSynthesizedDispatchDelay);
-}
-
 void SyntheticGestureController::StartTimer() {
   // TODO(sad): Change the interval to allow sending multiple events per begin
   // frame.
   dispatch_timer_.Start(
       FROM_HERE, base::TimeDelta::FromMicroseconds(16666),
       base::BindRepeating(
           [](base::WeakPtr<SyntheticGestureController> weak_ptr) {
             if (weak_ptr)
               weak_ptr->DispatchNextEvent(base::TimeTicks::Now());
           },
@@ skipping 30 matching lines @@
   }
   StartGesture(*pending_gesture_queue_.FrontGesture());
   return true;
 }
 
 void SyntheticGestureController::StartGesture(const SyntheticGesture& gesture) {
   TRACE_EVENT_ASYNC_BEGIN0("input,benchmark",
                            "SyntheticGestureController::running",
                            &gesture);
   if (!dispatch_timer_.IsRunning())
-    RequestBeginFrame();
+    StartTimer();
 }
 
 void SyntheticGestureController::StopGesture(
     const SyntheticGesture& gesture,
     const OnGestureCompleteCallback& completion_callback,
     SyntheticGesture::Result result) {
   DCHECK_NE(result, SyntheticGesture::GESTURE_RUNNING);
   TRACE_EVENT_ASYNC_END0("input,benchmark",
                          "SyntheticGestureController::running",
                          &gesture);
 
   completion_callback.Run(result);
 }
 
 SyntheticGestureController::GestureAndCallbackQueue::GestureAndCallbackQueue() {
 }
 
 SyntheticGestureController::GestureAndCallbackQueue::
     ~GestureAndCallbackQueue() {
 }
 
 }  // namespace content