Implement overscroll support for the virtual keyboard.

ui/keyboard/keyboard_controller.h

Index: ui/keyboard/keyboard_controller.h
diff --git a/ui/keyboard/keyboard_controller.h b/ui/keyboard/keyboard_controller.h
index 86cd12dd760cccca9e7e359dc8a8105bf7b51012..764169378805b0d0885c5cd7c3f5042e4aed5d29 100644
--- a/ui/keyboard/keyboard_controller.h
+++ b/ui/keyboard/keyboard_controller.h
@@ -9,6 +9,7 @@
 #include "base/event_types.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
+#include "ui/aura/client/virtual_keyboard_client.h"
 #include "ui/aura/window_observer.h"
 #include "ui/base/ime/input_method_observer.h"
 #include "ui/base/ime/text_input_type.h"
@@ -17,6 +18,9 @@
 
 namespace aura {
 class Window;
+namespace client {
+class VirtualKeyboardObserver;
+}
 }
 namespace gfx {
 class Rect;
@@ -34,8 +38,10 @@ class KeyboardControllerProxy;
 
 // Provides control of the virtual keyboard, including providing a container
 // and controlling visibility.
-class KEYBOARD_EXPORT KeyboardController : public ui::InputMethodObserver,
-                                           public aura::WindowObserver {
+class KEYBOARD_EXPORT KeyboardController
+    : public ui::InputMethodObserver,
+      public aura::WindowObserver,
+      public aura::client::VirtualKeyboardClient {
  public:
   // Different ways to hide the keyboard.
   enum HideReason {
@@ -70,9 +76,12 @@ class KEYBOARD_EXPORT KeyboardController : public ui::InputMethodObserver,
   // Notifies the keyboard observer for keyboard bounds changed.
   void NotifyKeyboardBoundsChanging(const gfx::Rect& new_bounds);
 
-  // Management of the observer list.
-  virtual void AddObserver(KeyboardControllerObserver* observer);
-  virtual void RemoveObserver(KeyboardControllerObserver* observer);
+  // Overridden from aura::client::VirtualKeyboardClient:
+  virtual void AddObserver(aura::client::VirtualKeyboardObserver* observer)
+      OVERRIDE;
+  virtual void RemoveObserver(aura::client::VirtualKeyboardObserver* observer)
+      OVERRIDE;
+  virtual bool IsOverscrollEnabled() OVERRIDE;
 
   KeyboardControllerProxy* proxy() { return proxy_.get(); }
 
@@ -124,7 +133,7 @@ class KEYBOARD_EXPORT KeyboardController : public ui::InputMethodObserver,
   bool lock_keyboard_;
   ui::TextInputType type_;
 
-  ObserverList<KeyboardControllerObserver> observer_list_;
+  ObserverList<aura::client::VirtualKeyboardObserver> observer_list_;
 
   base::WeakPtrFactory<KeyboardController> weak_factory_;