SetNeedsRedraw directly when updating a visible tile.

cc/test/delayed_raster_trigger.h

Index: cc/test/delayed_raster_trigger.h
diff --git a/cc/test/delayed_raster_trigger.h b/cc/test/delayed_raster_trigger.h
new file mode 100644
index 0000000000000000000000000000000000000000..4a969d66dc61b1f0399c4396844c979d753f3ea4
--- /dev/null
+++ b/cc/test/delayed_raster_trigger.h
@@ -0,0 +1,39 @@
+// 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.
+
+#ifndef CC_TEST_DELAYED_RASTER_TRIGGER_H_
+#define CC_TEST_DELAYED_RASTER_TRIGGER_H_
+
+#include <vector>
+
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+
+namespace base {
+class RunLoop;
+class SingleThreadTaskRunner;

[reveman, 2014/11/10 23:43:02]

what are these for?

[danakj, 2014/11/12 20:19:39]

Woops, from previous attempts to maket his go.

+}
+
+namespace cc {
+
+class DelayedRasterTrigger {

[vmpstr, 2014/11/10 22:47:04]

nit: This is just a DelayedTrigger right? (I'm not sure that Raster in the name
is helpful). 

Also, can you add a brief comment about how to use this class?

[danakj, 2014/11/12 20:19:40]

Done. Renamed the class to ThreadBlocker, and renamed the Begin/End methods to
Block/Unblock.

+ public:
+  DelayedRasterTrigger();
+  ~DelayedRasterTrigger();
+
+  void Delay();

[reveman, 2014/11/10 23:43:02]

The name of this confused me. How about Wait() instead? That seems to better
describe what it does.

[danakj, 2014/11/12 20:19:39]

Done.

+  void BeginDelay();
+  void EndDelay();
+
+ private:
+  base::Lock lock_;
+  bool should_delay_;
+  std::vector<base::WaitableEvent*> delayed_raster_tasks_;

[reveman, 2014/11/10 23:43:02]

hm, wouldn't it be enough with one WaitableEvent that multiple threads can wait
on? why the vector?

[danakj, 2014/11/12 20:19:39]

Right, thanks! Done.

+
+  DISALLOW_COPY_AND_ASSIGN(DelayedRasterTrigger);
+};
+
+}  // namespace cc
+
+#endif  // CC_TEST_DELAYED_RASTER_TRIGGER_H_