(not for commit) Simplified multi-threaded Ganesh with lock on Flush only.

cc/test/fake_tile_manager.cc

Index: cc/test/fake_tile_manager.cc
diff --git a/cc/test/fake_tile_manager.cc b/cc/test/fake_tile_manager.cc
index 04e7cd6b96fe6315766053373914eff5b68d969e..d43ab6c11af0a9cf78b333c70843596f885bb8de 100644
--- a/cc/test/fake_tile_manager.cc
+++ b/cc/test/fake_tile_manager.cc
@@ -21,9 +21,8 @@ class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
   void SetClient(TileTaskRunnerClient* client) override {}
   void Shutdown() override {}
   void ScheduleTasks(TileTaskQueue* queue) override {
-    for (TileTaskQueue::Item::Vector::const_iterator it = queue->items.begin();
-         it != queue->items.end(); ++it) {
-      RasterTask* task = it->task;
+    for (auto& item : queue->items) {
+      RasterTask* task = item.task->AsRasterTask();
 
       task->WillSchedule();
       task->ScheduleOnOriginThread(this);
@@ -33,11 +32,7 @@ class FakeTileTaskRunnerImpl : public TileTaskRunner, public TileTaskClient {
     }
   }
   void CheckForCompletedTasks() override {
-    for (RasterTask::Vector::iterator it = completed_tasks_.begin();
-         it != completed_tasks_.end();
-         ++it) {
-      RasterTask* task = it->get();
-
+    for (auto& task : completed_tasks_) {
       task->WillComplete();
       task->CompleteOnOriginThread(this);
       task->DidComplete();