Add initial GpuMemoryBufferSurfaceTexture implementation.

ui/gl/android/surface_texture_tracker.cc

Index: ui/gl/android/surface_texture_tracker.cc
diff --git a/ui/gl/android/surface_texture_tracker.cc b/ui/gl/android/surface_texture_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a5dd08588336395655f95572b79a19ca7edf12e2
--- /dev/null
+++ b/ui/gl/android/surface_texture_tracker.cc
@@ -0,0 +1,24 @@
+// 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 "ui/gl/android/surface_texture_tracker.h"
+
+namespace gfx {
+namespace {
+SurfaceTextureTracker* g_instance = NULL;

[epennerAtGoogle, 2014/03/12 00:45:06]

Same on this one. Can you use LazyInstance or comment why initialization races
are impossible?

[reveman, 2014/03/12 16:07:06]

Same answer.

+}  // namespace
+
+// static
+SurfaceTextureTracker* SurfaceTextureTracker::GetInstance() {

[epennerAtGoogle, 2014/03/12 00:45:06]

This is a lot better than an 'extern' but not _huge_ amount better ;). What I'm
worried about is this becoming an extra item that prevents us from using
out-of-proc GPU which otherwise just has one blocking issue IIUC.

I suppose we can just disable this feature if we do that, so I'm okay with it
for now. Sievers@, what's your thoughts?

[reveman, 2014/03/12 16:07:06]

I'd like to get this working with out-of-proc GPU asap but thought it'd be
better to land this first and do that as a follow up.

The idea is that none of this would change in out-of-proc GPU mode. This
instance would just be set to a different implementation by the GPU service
code.

[epennerAtGoogle, 2014/03/12 19:46:28]

If sievers@ is okay with it then no worries here.

+  DCHECK(g_instance);
+  return g_instance;
+}
+
+// static
+void SurfaceTextureTracker::InitInstance(SurfaceTextureTracker* tracker) {
+  DCHECK(!g_instance || !tracker);
+  g_instance = tracker;
+}
+
+}  // namespace gfx