[VSync Queue] Flush input in CommitComplete()

cc/trees/layer_tree_host_impl.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/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 224 matching lines @@
       micro_benchmark_controller_(this),
       task_graph_runner_(task_graph_runner),
       id_(id),
       requires_high_res_to_draw_(false),
       is_likely_to_require_a_draw_(false),
       has_valid_compositor_frame_sink_(false),
       mutator_(nullptr),
       scroll_animating_latched_node_id_(ScrollTree::kInvalidNodeId),
       has_scrolled_by_wheel_(false),
       has_scrolled_by_touch_(false),
-      touchpad_and_wheel_scroll_latching_enabled_(false) {
+      touchpad_and_wheel_scroll_latching_enabled_(false),
+      impl_thread_phase_(ImplThreadPhase::IDLE) {
   DCHECK(mutator_host_);
   mutator_host_->SetMutatorHostClient(this);
 
   DCHECK(task_runner_provider_->IsImplThread());
   DidVisibilityChange(this, visible_);
 
   SetDebugState(settings.initial_debug_state);
 
   // LTHI always has an active tree.
   active_tree_ = base::MakeUnique<LayerTreeImpl>(
@@ skipping 77 matching lines @@
   if (compositor_frame_sink_)
     compositor_frame_sink_->ForceReclaimResources();
 
   if (!CommitToActiveTree())
     CreatePendingTree();
 }
 
 void LayerTreeHostImpl::CommitComplete() {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::CommitComplete");
 
+  if (input_handler_client_ && impl_thread_phase_ == ImplThreadPhase::IDLE)

[sunnyps, 2017/05/03 18:37:13]

nit: can you please add a comment explaining why we're doing this here?

[chongz, 2017/05/03 20:32:33]

Done.

+    input_handler_client_->DeliverInputForBeginFrame();
+
   UpdateSyncTreeAfterCommitOrImplSideInvalidation();
   micro_benchmark_controller_.DidCompleteCommit();
 }
 
 void LayerTreeHostImpl::UpdateSyncTreeAfterCommitOrImplSideInvalidation() {
   sync_tree()->InvalidateRegionForImages(
       tile_manager_.TakeImagesToInvalidateOnSyncTree());
 
   if (CommitToActiveTree()) {
     // We have to activate animations here or "IsActive()" is true on the layers
@@ skipping 1550 matching lines @@
     SetNeedsRedraw();
   }
 
   if (input_handler_client_)
     input_handler_client_->DeliverInputForBeginFrame();
 
   Animate();
 
   for (auto* it : video_frame_controllers_)
     it->OnBeginFrame(args);
+
+  impl_thread_phase_ = ImplThreadPhase::INSIDE_IMPL_FRAME;
 }
 
 void LayerTreeHostImpl::DidFinishImplFrame() {
+  impl_thread_phase_ = ImplThreadPhase::IDLE;
   current_begin_frame_tracker_.Finish();
   decoded_image_tracker_.NotifyFrameFinished();
 }
 
 void LayerTreeHostImpl::UpdateViewportContainerSizes() {
   LayerImpl* inner_container = active_tree_->InnerViewportContainerLayer();
   LayerImpl* outer_container = active_tree_->OuterViewportContainerLayer();
 
   if (!inner_container)
     return;
@@ skipping 2370 matching lines @@
 }
 
 void LayerTreeHostImpl::UpdateScrollSourceInfo(bool is_wheel_scroll) {
   if (is_wheel_scroll)
     has_scrolled_by_wheel_ = true;
   else
     has_scrolled_by_touch_ = true;
 }
 
 }  // namespace cc