Revert of Implement and test task runners in RasterWorkerPool. (patchset #9 id:160001 of https://codereview.chromium.org/1254003003/ )

Reason for revert:
Suspected of breaking Linux Tests (dbg) bot. RasterWorkerPool_SequencedTaskRunnerTest_0.SequentialNestable is failing. http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests%20%28dbg%29/builds/1246

Original issue's description:
> Implement and test task runners in RasterWorkerPool.
>
> This CL moves RasterWorkerPool outside render_thread_impl.h and
> in its own file, implements TaskRunner and SequencedTaskRunner
> on top of it and properly tests the two implementations.
>
> BUG=
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/37808ab81754acebe81aaa14c87ab328e77e2c46
> Cr-Commit-Position: refs/heads/master@{#341654}

TBR=dalecurtis@chromium.org,piman@chromium.org,reveman@chromium.org,dcastagna@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1270093003

Cr-Commit-Position: refs/heads/master@{#341701}

2 files changed, 0 insertions, 15 deletions

diff --git a/cc/raster/task_graph_runner.cc b/cc/raster/task_graph_runner.cc
index 4cc912f..c810aa5 100644
--- a/cc/raster/task_graph_runner.cc
+++ b/cc/raster/task_graph_runner.cc
@@ -349,18 +349,6 @@ void TaskGraphRunner::Shutdown() {
   has_ready_to_run_tasks_cv_.Signal();
 }
 
-void TaskGraphRunner::FlushForTesting() {
-  base::AutoLock lock(lock_);
-
-  while (std::find_if(namespaces_.begin(), namespaces_.end(),
-                      [](const TaskNamespaceMap::value_type& entry) {
-                        return !HasFinishedRunningTasksInNamespace(
-                            &entry.second);
-                      }) != namespaces_.end()) {
-    has_namespaces_with_finished_running_tasks_cv_.Wait();
-  }
-}
-
 void TaskGraphRunner::Run() {
   base::AutoLock lock(lock_);
 
diff --git a/cc/raster/task_graph_runner.h b/cc/raster/task_graph_runner.h
index d6d4191..bb55afc 100644
--- a/cc/raster/task_graph_runner.h
+++ b/cc/raster/task_graph_runner.h
@@ -137,9 +137,6 @@ class CC_EXPORT TaskGraphRunner {
   // Warning: if the TaskGraphRunner remains busy, it may never quit.
   void Shutdown();
 
-  // Wait for all the tasks to finish running on all the namespaces.
-  void FlushForTesting();
-
  private:
   struct PrioritizedTask {
     typedef std::vector<PrioritizedTask> Vector;