Create single thread synchronous task graph runner when necessary with gpu disabled.

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 <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 2020 matching lines @@
 
 void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
     scoped_ptr<TileTaskWorkerPool>* tile_task_worker_pool,
     scoped_ptr<ResourcePool>* resource_pool,
     scoped_ptr<ResourcePool>* staging_resource_pool) {
   base::SingleThreadTaskRunner* task_runner =
       proxy_->HasImplThread() ? proxy_->ImplThreadTaskRunner()
                               : proxy_->MainThreadTaskRunner();
   DCHECK(task_runner);
 
+  // Pass the single-threaded synchronous task graph runner to the worker pool
+  // if we're in synchronous single-threaded mode.
+  TaskGraphRunner* task_graph_runner = task_graph_runner_;
+  if (IsSynchronousSingleThreaded()) {
+    DCHECK(!single_thread_synchronous_task_graph_runner_);
+    single_thread_synchronous_task_graph_runner_.reset(new TaskGraphRunner);
+    task_graph_runner = single_thread_synchronous_task_graph_runner_.get();
+  }
+
   ContextProvider* context_provider = output_surface_->context_provider();
   if (!context_provider) {
     *resource_pool =
         ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);
 
     *tile_task_worker_pool = BitmapTileTaskWorkerPool::Create(
         task_runner, task_graph_runner_, resource_provider_.get());

[vmpstr, 2015/05/14 20:00:19]

Is this supposed to be using task_graph_runner (the local variable)?

I don't understand why this is fixing it. Is it the fact that we use
single_thread_synchronous_task_graph_runner_ directly somewhere? and
tile_Task_worker_pool doesn't really matter?

     return;
   }
 
-  // Pass the single-threaded synchronous task graph runner to the worker pool
-  // if we're in synchronous single-threaded mode.
-  TaskGraphRunner* task_graph_runner = task_graph_runner_;
-  if (IsSynchronousSingleThreaded()) {
-    DCHECK(!single_thread_synchronous_task_graph_runner_);
-    single_thread_synchronous_task_graph_runner_.reset(new TaskGraphRunner);
-    task_graph_runner = single_thread_synchronous_task_graph_runner_.get();
-  }
-
   if (use_gpu_rasterization_) {
     *resource_pool =
         ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);
 
     int msaa_sample_count =
         use_msaa_ ? settings_.gpu_rasterization_msaa_sample_count : 0;
 
     *tile_task_worker_pool = GpuTileTaskWorkerPool::Create(
         task_runner, task_graph_runner, context_provider,
         resource_provider_.get(), settings_.use_distance_field_text,
@@ skipping 1329 matching lines @@
   new_target.SetToMin(layer_impl->MaxScrollOffset());
 
   curve->UpdateTarget(
       animation->TrimTimeToCurrentIteration(CurrentBeginFrameArgs().frame_time)
           .InSecondsF(),
       new_target);
 
   return true;
 }
 }  // namespace cc