[Remoting Android] Create Interfaces for GlDisplay

remoting/android/java/src/org/chromium/chromoting/RenderCallback.java

+// Copyright 2016 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.
+
+package org.chromium.chromoting;
+
+/**
+ * An interface with a set of rendering events that a caller can listen to.
+ */
+public interface RenderCallback {

[joedow, 2016/08/29 22:35:41]

Why separate this out from the Render stub?  It seems like this could be exposed
by the class implementing the RenderStub interface

[Yuwei, 2016/08/29 23:38:21]

I've considered having only one interface but
1. Currently multiple DesktopView/TouchInputHandler may be created in single
GlDisplay lifetime so we might need to have a special scoped RenderCallback
implementation for forwarding events for the lifetime of TouchInputHandler.
2. I think RenderStub and RenderCallback may not share the same functionality
and they may potentially be implemented by different classes.

#2 is not very important though. If we later resolve #1 (i.e. making
TouchInputHandler live as long as GlDisplay lives) then this interface can be a
part of RenderStub.

[Yuwei, 2016/08/30 22:39:12]

Put this back into RenderStub. We can later fix the leaking problem inside
TouchInputHandler.

+    /** An {@link Event} triggered when the client size is changed. */
+    Event<SizeChangedEventParameter> onClientSizeChanged();
+
+    /**
+     * An {@link Event} triggered when the size of the host desktop is changed.
+     */
+    Event<SizeChangedEventParameter> onHostSizeChanged();
+
+    /**
+     * An {@link} triggered when a frame has been rendered.
+     */
+    Event<Void> onCanvasRendered();
+}