SetNeedsRedraw directly when updating a visible tile.

cc/test/delayed_raster_trigger.cc

Index: cc/test/delayed_raster_trigger.cc
diff --git a/cc/test/delayed_raster_trigger.cc b/cc/test/delayed_raster_trigger.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b6a61cf42e662e35472bb00477eb60efb737ea80
--- /dev/null
+++ b/cc/test/delayed_raster_trigger.cc
@@ -0,0 +1,41 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/test/delayed_raster_trigger.h"
+
+#include "base/bind.h"
+
+namespace cc {
+
+DelayedRasterTrigger::DelayedRasterTrigger() : should_delay_(false) {
+}
+
+DelayedRasterTrigger::~DelayedRasterTrigger() {
+}
+
+void DelayedRasterTrigger::Delay() {
+  base::WaitableEvent waiter(false /* manual_reset */,
+                             false /* initially_signaled */);
+  {
+    base::AutoLock lock(lock_);
+    if (!should_delay_)
+      return;
+    delayed_raster_tasks_.push_back(&waiter);
+  }
+  waiter.Wait();
+}
+
+void DelayedRasterTrigger::BeginDelay() {
+  base::AutoLock lock(lock_);
+  should_delay_ = true;
+}
+
+void DelayedRasterTrigger::EndDelay() {
+  base::AutoLock lock(lock_);
+  should_delay_ = false;
+  for (const auto& waiter : delayed_raster_tasks_)
+    waiter->Signal();
+}
+
+}  // namespace cc