Add a BeginMainFrame fallback to MainThreadEventQueue.

content/renderer/input/main_thread_event_queue_unittest.cc

 // Copyright 2016 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 <stddef.h>
 
 #include <new>
 #include <utility>
 #include <vector>
 
@@ skipping 100 matching lines @@
       disabled_features.push_back(features::kRafAlignedMouseInputEvents.name);
     }
 
     feature_list_.InitFromCommandLine(base::JoinString(features, ","),
                                       base::JoinString(disabled_features, ","));
   }
 
   void SetUp() override {
     queue_ = new MainThreadEventQueue(this, main_task_runner_,
                                       &renderer_scheduler_, true);
+    queue_->set_use_raf_fallback_timer(false);
   }
 
   bool HandleEvent(WebInputEvent& event, InputEventAckState ack_result) {
     return queue_->HandleEvent(ui::WebInputEventTraits::Clone(event),
                                ui::LatencyInfo(), DISPATCH_TYPE_BLOCKING,
                                ack_result);
   }
 
   void RunClosure(unsigned closure_id) {
     std::unique_ptr<HandledTask> closure(new HandledClosure(closure_id));
@@ skipping 955 matching lines @@
             static_cast<const WebTouchEvent&>(
                 handled_tasks_.at(0)->taskAsEvent()->Event())
                 .dispatch_type);
   EXPECT_EQ(WebInputEvent::kBlocking,
             static_cast<const WebTouchEvent&>(
                 handled_tasks_.at(1)->taskAsEvent()->Event())
                 .dispatch_type);
 }
 
 }  // namespace content