Introduce ViewRoot to forward input/view events to native

ui/android/view_client.h

Index: ui/android/view_client.h
diff --git a/ui/android/view_client.h b/ui/android/view_client.h
new file mode 100644
index 0000000000000000000000000000000000000000..ea99f1e700d8a16f6f21ce0f0894ad354783764d
--- /dev/null
+++ b/ui/android/view_client.h
@@ -0,0 +1,23 @@
+// 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.
+
+#ifndef UI_ANDROID_VIEW_CLIENT_H_
+#define UI_ANDROID_VIEW_CLIENT_H_
+
+#include "ui/android/ui_android_export.h"
+
+namespace ui {
+
+// Client interface used to forward events from Java to native views.
+// Calls not handled by a client are dispatched to its children along
+// the hierarchy of ViewAndroid. Overriden method should return true
+// to indicate that the event was handled and stop the processing.
+class UI_ANDROID_EXPORT ViewClient {
+ public:
+  virtual bool OnPhysicalBackingSizeChanged(int width, int height);

[boliu, 2016/12/06 00:34:14]

if this were touch events, then returning a bool would make sense

but why would anything want to stop propagating a size change? I guess I need to
look at actual implementation to see what uses this, but this seems odd, just
looking at ui code

[Jinsuk Kim, 2016/12/06 07:35:07]

Not really a good example for the change :/

Turned to void. Still not sure why current code does not update all the RWVHA.

+};
+
+}  // namespace ui
+
+#endif  // UI_ANDROID_VIEW_CLIENT_H_