Reland "Throttle resource message requests during user interaction"

content/renderer/scheduler/renderer_scheduler_impl.cc

 // Copyright 2014 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/renderer/scheduler/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 118 matching lines @@
 void RendererSchedulerImpl::UpdateForInputEvent() {
   base::AutoLock lock(incoming_signals_lock_);
   if (last_input_time_.is_null()) {
     // Update scheduler policy if should start a new compositor policy mode.
     policy_may_need_update_.SetLocked(true);
     PostUpdatePolicyOnControlRunner(base::TimeDelta());
   }
   last_input_time_ = Now();
 }
 
+bool RendererSchedulerImpl::ShouldAnticipateHighPriorityWork() {
+  main_thread_checker_.CalledOnValidThread();
+  if (!task_queue_manager_)
+    return false;
+
+  MaybeUpdatePolicy();
+  return SchedulerPolicy() == COMPOSITOR_PRIORITY_POLICY;
+}
+
 bool RendererSchedulerImpl::ShouldYieldForHighPriorityWork() {
   main_thread_checker_.CalledOnValidThread();
   if (!task_queue_manager_)
     return false;
 
   MaybeUpdatePolicy();
   // We only yield if we are in the compositor priority and there is compositor
   // work outstanding. Note: even though the control queue is higher priority
   // we don't yield for it since these tasks are not user-provided work and they
   // are only intended to run before the next task, not interrupt the tasks.
+  // Note: This function could conceivable be implemented in terms of
+  // |ShouldAnticipateHighPriorityWork|, but for clarity is not.
   return SchedulerPolicy() == COMPOSITOR_PRIORITY_POLICY &&
          !task_queue_manager_->IsQueueEmpty(COMPOSITOR_TASK_QUEUE);
 }
 
 void RendererSchedulerImpl::CurrentIdleTaskDeadlineCallback(
     base::TimeTicks* deadline_out) const {
   main_thread_checker_.CalledOnValidThread();
   *deadline_out = estimated_next_frame_begin_;
 }
 
@@ skipping 147 matching lines @@
   state->SetDouble("last_input_time",
                    (last_input_time_ - base::TimeTicks()).InMillisecondsF());
   state->SetDouble(
       "estimated_next_frame_begin",
       (estimated_next_frame_begin_ - base::TimeTicks()).InMillisecondsF());
 
   return state;
 }
 
 }  // namespace content