Add ContentVideoViewOverlay to AVDA.

media/base/android/android_overlay.h

+// Copyright 2017 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 MEDIA_BASE_ANDROID_ANDROID_OVERLAY_H_
+#define MEDIA_BASE_ANDROID_ANDROID_OVERLAY_H_
+
+#include "base/android/scoped_java_ref.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "media/base/media_export.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gl/android/scoped_java_surface.h"
+
+namespace media {
+
+// Client interface to an AndroidOverlay.  Once constructed, you can expect to
+// receive zero or one ReadyCallbacks, and one DestroyedCallback.
+// Upon receiving ReadyCallback, you will have an Android Surface that you may
+// use until DestroyedCallback.  You may also move the surface (ScheduleLayout).
+// When SurfaceDestroyed arrives, you should stop using the Android Surface and

[watk, 2017/02/17 22:40:36]

The contract about what to do when SurfaceDestroyed is called is unclear. Also
s/SurfaceDestroyed arrives/DestroyedCallback is called/.

[liberato (no reviews please), 2017/03/07 21:30:25]

Done.

+// delete the AndroidOverlay instance.  Note that these calls are synchronous
+// in Android, so you should delete the AndroidOverlay surface as soon as
+// possible.  Other overlays might be blocked waiting.
+class MEDIA_EXPORT AndroidOverlay {
+ public:
+  // Called when the overlay is ready for use.  Use |j_surface()| to get it.
+  using ReadyCallback = base::Callback<void()>;

[watk, 2017/02/17 22:40:36]

Use the conventional "cb": ReadyCb?

[liberato (no reviews please), 2017/03/07 21:30:25]

done, though i used "CB" since it seems more common than "Cb"

+
+  // Called when the overlay has been destroyed.  This may be called before
+  // ReadyCallback.  It will be the last callback for the overlay.
+  using DestroyedCallback = base::Callback<void()>;
+
+  // Configuration used to create an overlay.
+  struct Config {
+   public:
+    Config();
+    Config(const Config&);
+    ~Config();
+
+    gfx::Rect rect;
+    // TODO(liberato): add format, etc. here.

[watk, 2017/02/17 22:40:36]

TODO doesn't seem necessary because we'll add things when we need to.

[liberato (no reviews please), 2017/03/07 21:30:25]

on a CL a while ago, an objection was raised that we coujld replace Config with
just gfx::Rect.  now that we have callbacks, i guess i don't need it anymore.

+
+    ReadyCallback ready_cb;
+    DestroyedCallback destroyed_cb;
+  };
+
+  virtual ~AndroidOverlay();
+
+  // Schedule a relayout of this overlay.  If called before the client is

[watk, 2017/02/17 22:40:36]

nit: here and elsewhere comments style is not in line with the style guide. This
part: 

These comments should be descriptive ("Opens the file") rather than imperative
("Open the file"); the comment describes the function, it does not tell the
function what to do.

[liberato (no reviews please), 2017/03/07 21:30:25]

nit++ :)  Done.

+  // notified that the surface is created, then the call will be ignored.
+  virtual void ScheduleLayout(const gfx::Rect& rect) = 0;
+
+  // Return the Java Surface object.

[watk, 2017/02/17 22:40:36]

nit: Don't think it needs a comment

[liberato (no reviews please), 2017/03/07 21:30:25]

i agree that it adds no value as written.  changed it to reiterate when one may
call it, rather than what it does.

+  const base::android::JavaRef<jobject>& j_surface() const {
+    return surface_.j_surface();
+  }
+
+ protected:
+  AndroidOverlay();
+
+  // Set the java surface that we'll provide.  Subclasses should provide this
+  // before sending ReadyCallback.
+  void SetJavaSurface(gl::ScopedJavaSurface);

[watk, 2017/02/17 22:40:36]

Doesn't seem necessary if subclasses can set surface_ themselves? You can just
say j_surface() is only valid after ReadyCb is called.

The closer this is to a pure virtual class, the better IMO.

[liberato (no reviews please), 2017/03/07 21:30:25]

true.  i'll just make j_surface() abstract and make it entirely the subclass's
problem.  i agree about pure virtual is better.  will rename from j_surface()
for style guide.  wanted to keep it the same as ScopedJavaSurface, but really
not to many folks will need ScopedJavaSurface directly if this works.

that will let me inline the AndroidOverlay *structors, too.

+
+  gl::ScopedJavaSurface surface_;
+  DISALLOW_COPY_AND_ASSIGN(AndroidOverlay);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_ANDROID_OVERLAY_H_