cc: Simplify task and its derived classes.

cc/raster/task_graph_runner_perftest.cc

Index: cc/raster/task_graph_runner_perftest.cc
diff --git a/cc/raster/task_graph_runner_perftest.cc b/cc/raster/task_graph_runner_perftest.cc
index f86bae571bfb4c344f9e871a77db7bf11258d39e..9483fdaadeb67323801a00909079aae190a732a0 100644
--- a/cc/raster/task_graph_runner_perftest.cc
+++ b/cc/raster/task_graph_runner_perftest.cc
@@ -23,13 +23,15 @@ static const int kTimeLimitMillis = 2000;
 static const int kWarmupRuns = 5;
 static const int kTimeCheckInterval = 10;
 
-class PerfTaskImpl : public Task {
+class PerfTaskImpl : public DependencyTask {
  public:
   typedef std::vector<scoped_refptr<PerfTaskImpl>> Vector;
 
   PerfTaskImpl() {}
 
-  // Overridden from Task:
+  // Overridden from DependencyTask:
+  void ScheduleOnOriginThread(DependencyTaskClient* client) override {}
+  void CompleteOnOriginThread(DependencyTaskClient* client) override {}
   void RunOnWorkerThread() override {}
 
   void Reset() { did_run_ = false; }
@@ -97,7 +99,7 @@ class TaskGraphRunnerPerfTest : public testing::Test {
     // Avoid unnecessary heap allocations by reusing the same graph and
     // completed tasks vector.
     TaskGraph graph;
-    Task::Vector completed_tasks;
+    DependencyTask::Vector completed_tasks;
 
     timer_.Reset();
     do {
@@ -139,7 +141,7 @@ class TaskGraphRunnerPerfTest : public testing::Test {
     // Avoid unnecessary heap allocations by reusing the same graph and
     // completed tasks vector.
     TaskGraph graph;
-    Task::Vector completed_tasks;
+    DependencyTask::Vector completed_tasks;
 
     size_t count = 0;
     timer_.Reset();
@@ -182,7 +184,7 @@ class TaskGraphRunnerPerfTest : public testing::Test {
     // Avoid unnecessary heap allocations by reusing the same graph and
     // completed tasks vector.
     TaskGraph graph;
-    Task::Vector completed_tasks;
+    DependencyTask::Vector completed_tasks;
 
     timer_.Reset();
     do {
@@ -263,7 +265,7 @@ class TaskGraphRunnerPerfTest : public testing::Test {
     }
   }
 
-  size_t CollectCompletedTasks(Task::Vector* completed_tasks) {
+  size_t CollectCompletedTasks(DependencyTask::Vector* completed_tasks) {
     DCHECK(completed_tasks->empty());
     task_graph_runner_->CollectCompletedTasks(namespace_token_,
                                               completed_tasks);