cc: Simplify task and its derived classes.

cc/tiles/tile_manager_unittest.cc

Index: cc/tiles/tile_manager_unittest.cc
diff --git a/cc/tiles/tile_manager_unittest.cc b/cc/tiles/tile_manager_unittest.cc
index 745fee4ca853a48a593c4839a87b8a14602f1d63..074240ed88222c46337af741320660478a802cb7 100644
--- a/cc/tiles/tile_manager_unittest.cc
+++ b/cc/tiles/tile_manager_unittest.cc
@@ -9,7 +9,6 @@
 #include "base/thread_task_runner_handle.h"
 #include "cc/playback/raster_source.h"
 #include "cc/playback/recording_source.h"
-#include "cc/raster/raster_buffer.h"
 #include "cc/resources/resource_pool.h"
 #include "cc/test/begin_frame_args_test.h"
 #include "cc/test/fake_impl_task_runner_provider.h"
@@ -1820,11 +1819,21 @@ TEST_F(TileManagerTest, LowResHasNoImage) {
 }
 
 // Fake TileTaskRunner that just no-ops all calls.
-class FakeTileTaskRunner : public TileTaskRunner, public TileTaskClient {
+class FakeTileTaskRunner : public TileTaskRunner {
  public:
   FakeTileTaskRunner() {}
   ~FakeTileTaskRunner() override {}
 
+  // RasterBufferProvider methods.
+  scoped_ptr<RasterBuffer> AcquireBufferForRaster(
+      const Resource* resource,
+      uint64_t resource_content_id,
+      uint64_t previous_content_id) override {
+    NOTREACHED();
+    return nullptr;
+  }
+  void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override {}
+
   // TileTaskRunner methods.
   void Shutdown() override {}
   void CheckForCompletedTasks() override {}
@@ -1836,16 +1845,6 @@ class FakeTileTaskRunner : public TileTaskRunner, public TileTaskClient {
   }
 
   void ScheduleTasks(TaskGraph* graph) override {}
-
-  // TileTaskClient methods.
-  scoped_ptr<RasterBuffer> AcquireBufferForRaster(
-      const Resource* resource,
-      uint64_t resource_content_id,
-      uint64_t previous_content_id) override {
-    NOTREACHED();
-    return nullptr;
-  }
-  void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override {}
 };
 
 // Fake TileTaskRunner that just cancels all scheduled tasks immediately.
@@ -1858,7 +1857,7 @@ class CancellingTileTaskRunner : public FakeTileTaskRunner {
     // Just call CompleteOnOriginThread on each item in the queue. As none of
     // these items have run yet, they will be treated as cancelled tasks.
     for (const auto& node : graph->nodes) {
-      static_cast<TileTask*>(node.task)->CompleteOnOriginThread(this);
+      node.task->CompleteOnOriginThread();
     }
   }
 };
@@ -1931,17 +1930,7 @@ class VerifyResourceContentIdTileTaskRunner : public FakeTileTaskRunner {
       : expected_resource_id_(expected_resource_id) {}
   ~VerifyResourceContentIdTileTaskRunner() override {}
 
-  void ScheduleTasks(TaskGraph* graph) override {
-    for (const auto& node : graph->nodes) {
-      TileTask* task = static_cast<TileTask*>(node.task);
-      // Triggers a call to AcquireBufferForRaster.
-      task->ScheduleOnOriginThread(this);
-      // Calls TileManager as though task was cancelled.
-      task->CompleteOnOriginThread(this);
-    }
-  }
-
-  // TileTaskClient methods.
+  // RasterBufferProvider methods.
   scoped_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource,
       uint64_t resource_content_id,
@@ -1950,6 +1939,16 @@ class VerifyResourceContentIdTileTaskRunner : public FakeTileTaskRunner {
     return nullptr;
   }
 
+  void ScheduleTasks(TaskGraph* graph) override {
+    for (const auto& node : graph->nodes) {
+      Task* task = node.task;
+      // Triggers a call to AcquireBufferForRaster.
+      task->ScheduleOnOriginThread();
+      // Calls TileManager as though task was cancelled.
+      task->CompleteOnOriginThread();
+    }
+  }
+
  private:
   uint64_t expected_resource_id_;
 };