cc: Update scroll offset before property tree scrolling and animation.

cc/trees/layer_tree_host_in_process.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_in_process.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 403 matching lines @@
 }
 
 void LayerTreeHostInProcess::RequestMainFrameUpdate() {
   client_->UpdateLayerTreeHost();
 }
 
 // This function commits the LayerTreeHost to an impl tree. When modifying
 // this function, keep in mind that the function *runs* on the impl thread! Any
 // code that is logically a main thread operation, e.g. deletion of a Layer,
 // should be delayed until the LayerTreeHostInProcess::CommitComplete, which
-// will run
-// after the commit, but on the main thread.
+// will run after the commit, but on the main thread.
 void LayerTreeHostInProcess::FinishCommitOnImplThread(
     LayerTreeHostImpl* host_impl) {
   DCHECK(!IsRemoteServer());
-  DCHECK(task_runner_provider_->IsImplThread());
+  // The function may also be called by single threaded unit test.
+  DCHECK(task_runner_provider_->IsImplThread() ||
+         !task_runner_provider_->ImplThreadTaskRunner());

[ajuma, 2016/10/07 18:38:30]

Instead of calling this directly from your test, can you use a LayerTreeTest
(e.g. LayerTreeHostUnitTest or LayerTreeHostScrollTest) where this gets called
in the usual way?

 
   bool is_new_trace;
   TRACE_EVENT_IS_NEW_TRACE(&is_new_trace);
   if (is_new_trace &&
       frame_viewer_instrumentation::IsTracingLayerTreeSnapshots() &&
       layer_tree_->root_layer()) {
     LayerTreeHostCommon::CallFunctionForEveryLayer(
         layer_tree_.get(), [](Layer* layer) { layer->DidBeginTracing(); });
   }
 
@@ skipping 31 matching lines @@
   host_impl->SetDebugState(debug_state_);
 
   sync_tree->set_ui_resource_request_queue(
       ui_resource_manager_->TakeUIResourcesRequests());
 
   {
     TRACE_EVENT0("cc", "LayerTreeHostInProcess::PushProperties");
 
     TreeSynchronizer::PushLayerProperties(layer_tree_.get(), sync_tree);
 
+    // This must happen after synchronizing property trees and after pushing
+    // properties, which updates the clobber_active_value flag.
+    sync_tree->UpdatePropertyTreeScrollOffset(layer_tree_->property_trees());
+
     // This must happen after synchronizing property trees and after push
     // properties, which updates property tree indices, but before animation
     // host pushes properties as animation host push properties can change
     // Animation::InEffect and we want the old InEffect value for updating
     // property tree scrolling and animation.
     sync_tree->UpdatePropertyTreeScrollingAndAnimationFromMainThread();
 
     TRACE_EVENT0("cc", "LayerTreeHostInProcess::AnimationHost::PushProperties");
     DCHECK(host_impl->animation_host());
     layer_tree_->animation_host()->PushPropertiesTo(
         host_impl->animation_host());
   }
 
-  // This must happen after synchronizing property trees and after pushing
-  // properties, which updates the clobber_active_value flag.
-  sync_tree->UpdatePropertyTreeScrollOffset(layer_tree_->property_trees());
-
   micro_benchmark_controller_.ScheduleImplBenchmarks(host_impl);
   layer_tree_->property_trees()->ResetAllChangeTracking();
 }
 
 void LayerTreeHostInProcess::WillCommit() {
   swap_promise_manager_.WillCommit();
   client_->WillCommit();
 }
 
 void LayerTreeHostInProcess::UpdateHudLayer() {}
@@ skipping 530 matching lines @@
 
   debug_state_.FromProtobuf(proto.debug_state());
   has_gpu_rasterization_trigger_ = proto.has_gpu_rasterization_trigger();
   content_is_suitable_for_gpu_rasterization_ =
       proto.content_is_suitable_for_gpu_rasterization();
   id_ = proto.id();
   next_commit_forces_redraw_ = proto.next_commit_forces_redraw();
 }
 
 }  // namespace cc