Hoist begin frame sources out of scheduler

cc/trees/proxy_impl.cc

 // Copyright 2015 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 "cc/trees/proxy_impl.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 42 matching lines @@
       commit_completion_event_(nullptr),
       next_frame_is_newly_committed_frame_(false),
       inside_draw_(false),
       input_throttled_until_commit_(false),
       task_runner_provider_(task_runner_provider),
       smoothness_priority_expiration_notifier_(
           task_runner_provider->ImplThreadTaskRunner(),
           base::Bind(&ProxyImpl::RenewTreePriority, base::Unretained(this)),
           base::TimeDelta::FromSecondsD(
               kSmoothnessTakesPriorityExpirationDelay)),
-      external_begin_frame_source_(std::move(external_begin_frame_source)),
+      begin_frame_source_(std::move(external_begin_frame_source)),
       rendering_stats_instrumentation_(
           layer_tree_host->rendering_stats_instrumentation()),
       channel_impl_(channel_impl) {
   TRACE_EVENT0("cc", "ProxyImpl::ProxyImpl");
   DCHECK(IsImplThread());
   DCHECK(IsMainThreadBlocked());
 
   layer_tree_host_impl_ = layer_tree_host->CreateLayerTreeHostImpl(this);
 
   SchedulerSettings scheduler_settings(
       layer_tree_host->settings().ToSchedulerSettings());
 
   scoped_ptr<CompositorTimingHistory> compositor_timing_history(
       new CompositorTimingHistory(
           scheduler_settings.using_synchronous_renderer_compositor,
           CompositorTimingHistory::RENDERER_UMA,
           rendering_stats_instrumentation_));
 
-  scheduler_ = Scheduler::Create(this, scheduler_settings, layer_tree_host_id_,
-                                 task_runner_provider_->ImplThreadTaskRunner(),
-                                 external_begin_frame_source_.get(),
-                                 std::move(compositor_timing_history));
+  if (!scheduler_settings.throttle_frame_production) {
+    // Unthrottled source takes precedence over external sources.
+    begin_frame_source_ = BackToBackBeginFrameSource::Create(
+        task_runner_provider_->ImplThreadTaskRunner());
+  }
+  BeginFrameSource* frame_source = begin_frame_source_.get();
+  if (!frame_source) {
+    synthetic_frame_source_ = SyntheticBeginFrameSource::Create(
+        task_runner_provider_->ImplThreadTaskRunner(),
+        BeginFrameArgs::DefaultInterval());
+    frame_source = synthetic_frame_source_.get();
+  }
+  scheduler_ =
+      Scheduler::Create(this, scheduler_settings, layer_tree_host_id_,
+                        task_runner_provider_->ImplThreadTaskRunner(),
+                        frame_source, std::move(compositor_timing_history));
 
   DCHECK_EQ(scheduler_->visible(), layer_tree_host_impl_->visible());
 }
 
 ProxyImpl::BlockedMainCommitOnly::BlockedMainCommitOnly()
     : layer_tree_host(nullptr) {}
 
 ProxyImpl::BlockedMainCommitOnly::~BlockedMainCommitOnly() {}
 
 ProxyImpl::~ProxyImpl() {
   TRACE_EVENT0("cc", "ProxyImpl::~ProxyImpl");
   DCHECK(IsImplThread());
   DCHECK(IsMainThreadBlocked());
 
   scheduler_ = nullptr;
-  external_begin_frame_source_ = nullptr;
+  begin_frame_source_ = nullptr;
+  synthetic_frame_source_ = nullptr;
   layer_tree_host_impl_ = nullptr;
   // We need to explicitly shutdown the notifier to destroy any weakptrs it is
   // holding while still on the compositor thread. This also ensures any
   // callbacks holding a ProxyImpl pointer are cancelled.
   smoothness_priority_expiration_notifier_.Shutdown();
 }
 
 void ProxyImpl::UpdateTopControlsStateOnImpl(TopControlsState constraints,
                                              TopControlsState current,
                                              bool animate) {
@@ skipping 157 matching lines @@
 void ProxyImpl::DidLoseOutputSurfaceOnImplThread() {
   TRACE_EVENT0("cc", "ProxyImpl::DidLoseOutputSurfaceOnImplThread");
   DCHECK(IsImplThread());
   channel_impl_->DidLoseOutputSurface();
   scheduler_->DidLoseOutputSurface();
 }
 
 void ProxyImpl::CommitVSyncParameters(base::TimeTicks timebase,
                                       base::TimeDelta interval) {
   DCHECK(IsImplThread());
-  scheduler_->CommitVSyncParameters(timebase, interval);
+  if (!synthetic_frame_source_)
+    return;
+
+  if (interval == base::TimeDelta()) {
+    // TODO(brianderson): We should not be receiving 0 intervals.
+    interval = BeginFrameArgs::DefaultInterval();
+  }
+  synthetic_frame_source_->OnUpdateVSyncParameters(timebase, interval);
 }
 
 void ProxyImpl::SetEstimatedParentDrawTime(base::TimeDelta draw_time) {
   DCHECK(IsImplThread());
   scheduler_->SetEstimatedParentDrawTime(draw_time);
 }
 
 void ProxyImpl::DidSwapBuffersOnImplThread() {
   DCHECK(IsImplThread());
   scheduler_->DidSwapBuffers();
@@ skipping 368 matching lines @@
 bool ProxyImpl::IsMainThreadBlocked() const {
   return task_runner_provider_->IsMainThreadBlocked();
 }
 
 ProxyImpl::BlockedMainCommitOnly& ProxyImpl::blocked_main_commit() {
   DCHECK(IsMainThreadBlocked() && commit_completion_event_);
   return main_thread_blocked_commit_vars_unsafe_;
 }
 
 }  // namespace cc