Implements onBoundsChanged event in virtualKeyboardPrivate namespace

ui/keyboard/keyboard_controller_proxy.h

Index: ui/keyboard/keyboard_controller_proxy.h
diff --git a/ui/keyboard/keyboard_controller_proxy.h b/ui/keyboard/keyboard_controller_proxy.h
index 2c91446460815b39bb4eee56fb7d20ff9295aa4a..f927849eb2e8b25c433c2ebe442458d2d6ed7e2e 100644
--- a/ui/keyboard/keyboard_controller_proxy.h
+++ b/ui/keyboard/keyboard_controller_proxy.h
@@ -31,6 +31,8 @@ class Shadow;
 
 namespace keyboard {
 
+class KeyboardController;
+
 // A proxy used by the KeyboardController to get access to the virtual
 // keyboard window.
 class KEYBOARD_EXPORT KeyboardControllerProxy : public aura::WindowObserver {
@@ -101,6 +103,11 @@ class KEYBOARD_EXPORT KeyboardControllerProxy : public aura::WindowObserver {
   // provide one.
   virtual void ReloadKeyboardIfNeeded();
 
+  // KeyboardController owns KeyboardControllerProxy so KeyboardControllerProxy
+  // or its subclasses should not take ownership of the |controller|.
+  // |controller| can be null when KeyboardController is destroying.
+  virtual void SetController(KeyboardController* controller) {}
+
  protected:
   // The implementation can choose to setup the WebContents before the virtual
   // keyboard page is loaded (e.g. install a WebContentsObserver).