cc: Change tile manager to have a raw ptr for the task runner.

This patch changes |task_runner_| member in tile manager to be a raw
pointer instead of a scoped_refptr. All the codepaths seem to guarantee
that the task runner outlives tile manager, so there is no need to
create a scoped_refptr a raw pointer at tile manager creation time.

R=ericrk, reveman
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/2026663005
Cr-Commit-Position: refs/heads/master@{#397241}

cc/test/fake_tile_manager.cc

@@ -27,7 +27,7 @@ base::LazyInstance<FakeTileTaskManagerImpl> g_fake_tile_task_manager =
 
 FakeTileManager::FakeTileManager(TileManagerClient* client)
     : TileManager(client,
-                  base::ThreadTaskRunnerHandle::Get(),
+                  base::ThreadTaskRunnerHandle::Get().get(),
                   std::numeric_limits<size_t>::max(),
                   false /* use_partial_raster */),
       image_decode_controller_(
@@ -41,7 +41,7 @@ FakeTileManager::FakeTileManager(TileManagerClient* client)
 FakeTileManager::FakeTileManager(TileManagerClient* client,
                                  ResourcePool* resource_pool)
     : TileManager(client,
-                  base::ThreadTaskRunnerHandle::Get(),
+                  base::ThreadTaskRunnerHandle::Get().get(),
                   std::numeric_limits<size_t>::max(),
                   false /* use_partial_raster */),
       image_decode_controller_(

cc/tiles/tile_manager.cc

@@ -282,7 +282,7 @@ class TaskSetFinishedTaskImpl : public TileTask {
   }
 
  private:
-  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  base::SequencedTaskRunner* task_runner_;
   const base::Closure on_task_set_finished_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskSetFinishedTaskImpl);
@@ -305,11 +305,11 @@ RasterTaskCompletionStatsAsValue(const RasterTaskCompletionStats& stats) {
 }
 
 TileManager::TileManager(TileManagerClient* client,
-                         scoped_refptr<base::SequencedTaskRunner> task_runner,
+                         base::SequencedTaskRunner* task_runner,
                          size_t scheduled_raster_task_limit,
                          bool use_partial_raster)
     : client_(client),
-      task_runner_(std::move(task_runner)),
+      task_runner_(task_runner),
       resource_pool_(nullptr),
       tile_task_manager_(nullptr),
       scheduled_raster_task_limit_(scheduled_raster_task_limit),
@@ -319,10 +319,10 @@ TileManager::TileManager(TileManagerClient* client,
       did_check_for_completed_tasks_since_last_schedule_tasks_(true),
       did_oom_on_last_assign_(false),
       more_tiles_need_prepare_check_notifier_(
-          task_runner_.get(),
+          task_runner_,
           base::Bind(&TileManager::CheckIfMoreTilesNeedToBePrepared,
                      base::Unretained(this))),
-      signals_check_notifier_(task_runner_.get(),
+      signals_check_notifier_(task_runner_,
                               base::Bind(&TileManager::CheckAndIssueSignals,
                                          base::Unretained(this))),
       has_scheduled_tile_tasks_(false),
@@ -1173,7 +1173,7 @@ TileManager::ScheduledTasksStateAsValue() const {
 scoped_refptr<TileTask> TileManager::CreateTaskSetFinishedTask(
     void (TileManager::*callback)()) {
   return make_scoped_refptr(new TaskSetFinishedTaskImpl(
-      task_runner_.get(),
+      task_runner_,
       base::Bind(callback, task_set_finished_weak_ptr_factory_.GetWeakPtr())));
 }
 

cc/tiles/tile_manager.h

@@ -96,7 +96,7 @@ RasterTaskCompletionStatsAsValue(const RasterTaskCompletionStats& stats);
 class CC_EXPORT TileManager {
  public:
   TileManager(TileManagerClient* client,
-              scoped_refptr<base::SequencedTaskRunner> task_runner,
+              base::SequencedTaskRunner* task_runner,
               size_t scheduled_raster_task_limit,
               bool use_partial_raster);
   virtual ~TileManager();
@@ -271,7 +271,7 @@ class CC_EXPORT TileManager {
   ScheduledTasksStateAsValue() const;
 
   TileManagerClient* client_;
-  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  base::SequencedTaskRunner* task_runner_;
   ResourcePool* resource_pool_;
   TileTaskManager* tile_task_manager_;
   GlobalStateThatImpactsTilePriority global_state_;

cc/trees/layer_tree_host_impl.cc

@@ -218,9 +218,6 @@ LayerTreeHostImpl::LayerTreeHostImpl(
                                       !settings.single_thread_proxy_scheduler),
       // Must be initialized after is_synchronous_single_threaded_ and
       // task_runner_provider_.
-      // TODO(vmpstr): TileManager takes a scoped reftr for the task runner,
-      // figure out if it actually needs a ref or whether it can use a raw
-      // pointer.
       tile_manager_(new TileManager(this,
                                     GetTaskRunner(),
                                     is_synchronous_single_threaded_