cc: If SetDeferCommits(true) happens inside the main frame, abort it.

cc/trees/single_thread_proxy.cc

 // Copyright 2011 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/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 453 matching lines @@
     DebugScopedSetImplThread impl(task_runner_provider_);
     WillBeginImplFrame(begin_frame_args);
   }
 
   // Run the "main thread" and get it to commit.
   {
 #if DCHECK_IS_ON()
     DCHECK(inside_impl_frame_);
 #endif
     DoBeginMainFrame(begin_frame_args);
+    DoPainting();
     DoCommit();
 
     DCHECK_EQ(
         0u,
         layer_tree_host_->GetSwapPromiseManager()->num_queued_swap_promises())
         << "Commit should always succeed and transfer promises.";
   }
 
   // Finish the impl frame.
   {
@@ skipping 167 matching lines @@
         CommitEarlyOutReason::ABORTED_NOT_VISIBLE);
     return;
   }
 
   // Prevent new commits from being requested inside DoBeginMainFrame.
   // Note: We do not want to prevent SetNeedsAnimate from requesting
   // a commit here.
   commit_requested_ = true;
 
   DoBeginMainFrame(begin_frame_args);
+
+  // New commits requested inside UpdateLayers should be respected.
+  commit_requested_ = false;
+
+  // At this point the main frame may have deferred commits to avoid committing
+  // right now.
+  if (defer_commits_) {
+    TRACE_EVENT_INSTANT0("cc", "EarlyOut_DeferCommit_InsideBeginMainFrame",
+                         TRACE_EVENT_SCOPE_THREAD);
+    BeginMainFrameAbortedOnImplThread(
+        CommitEarlyOutReason::ABORTED_DEFERRED_COMMIT);
+    layer_tree_host_->DidBeginMainFrame();
+    return;
+  }
+
+  DoPainting();
 }
 
 void SingleThreadProxy::DoBeginMainFrame(
     const BeginFrameArgs& begin_frame_args) {
   // In the single-threaded case, the scale deltas should never be touched on
   // the impl layer tree. However, impl-side scroll deltas may be manipulated
   // directly via the InputHandler on the UI thread.
   std::unique_ptr<ScrollAndScaleSet> scroll_info =
       layer_tree_host_impl_->ProcessScrollDeltas();
   DCHECK_EQ(1.f, scroll_info->page_scale_delta);
   layer_tree_host_->ApplyScrollAndScale(scroll_info.get());
 
   layer_tree_host_->WillBeginMainFrame();
   layer_tree_host_->BeginMainFrame(begin_frame_args);
   layer_tree_host_->AnimateLayers(begin_frame_args.frame_time);
   layer_tree_host_->RequestMainFrameUpdate();
+}
 
-  // New commits requested inside UpdateLayers should be respected.
-  commit_requested_ = false;
-
+void SingleThreadProxy::DoPainting() {
   layer_tree_host_->UpdateLayers();
 
   // TODO(enne): SingleThreadProxy does not support cancelling commits yet,
   // search for CommitEarlyOutReason::FINISHED_NO_UPDATES inside
   // thread_proxy.cc
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->NotifyReadyToCommit();
 }
 
 void SingleThreadProxy::BeginMainFrameAbortedOnImplThread(
@@ skipping 81 matching lines @@
 void SingleThreadProxy::DidFinishImplFrame() {
   layer_tree_host_impl_->DidFinishImplFrame();
 #if DCHECK_IS_ON()
   DCHECK(inside_impl_frame_)
       << "DidFinishImplFrame called while not inside an impl frame!";
   inside_impl_frame_ = false;
 #endif
 }
 
 }  // namespace cc