cc: Simplify task and its derived classes.

cc/tiles/tile_manager_perftest.cc

Index: cc/tiles/tile_manager_perftest.cc
diff --git a/cc/tiles/tile_manager_perftest.cc b/cc/tiles/tile_manager_perftest.cc
index 7529e36e45f3bc4d1da4760fdf88bdefe11f3f38..1583a2652d12588e88597157807c86a6b0162ae9 100644
--- a/cc/tiles/tile_manager_perftest.cc
+++ b/cc/tiles/tile_manager_perftest.cc
@@ -37,13 +37,14 @@ static const int kTimeLimitMillis = 2000;
 static const int kWarmupRuns = 5;
 static const int kTimeCheckInterval = 10;
 
-class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
+class FakeTileTaskRunnerImpl : public TileTaskRunner,
+                               public DependencyTaskClient {
  public:
   // Overridden from TileTaskRunner:
   void Shutdown() override {}
   void ScheduleTasks(TaskGraph* graph) override {
     for (auto& node : graph->nodes) {
-      TileTask* task = static_cast<TileTask*>(node.task);
+      DependencyTask* task = node.task;
 
       task->WillSchedule();
       task->ScheduleOnOriginThread(this);
@@ -53,9 +54,9 @@ class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
     }
   }
   void CheckForCompletedTasks() override {
-    for (TileTask::Vector::iterator it = completed_tasks_.begin();
+    for (DependencyTask::Vector::iterator it = completed_tasks_.begin();
          it != completed_tasks_.end(); ++it) {
-      TileTask* task = it->get();
+      DependencyTask* task = it->get();
 
       task->WillComplete();
       task->CompleteOnOriginThread(this);
@@ -70,7 +71,7 @@ class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
     return ResourceFormatRequiresSwizzle(GetResourceFormat(must_support_alpha));
   }
 
-  // Overridden from TileTaskClient:
+  // Overridden from DependencyTaskClient:
   scoped_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource,
       uint64_t new_content_id,
@@ -80,7 +81,7 @@ class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
   void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override {}
 
  private:
-  TileTask::Vector completed_tasks_;
+  DependencyTask::Vector completed_tasks_;
 };
 base::LazyInstance<FakeTileTaskRunnerImpl> g_fake_tile_task_runner =
     LAZY_INSTANCE_INITIALIZER;