Plumb an overscroll callback form the compositor to the Android UI thread.

content/browser/android/content_view_core_impl.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 #define CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 
 #include <vector>
 
 #include "base/android/jni_helper.h"
@@ skipping 211 matching lines @@
   // |multiple| defines if it should support multi-select.
   // If not |multiple|, |selected_item| sets the initially selected item.
   // Otherwise, item's "checked" flag selects it.
   void ShowSelectPopupMenu(const std::vector<WebMenuItem>& items,
                            int selected_item,
                            bool multiple);
 
   void OnTabCrashed();
   void UpdateContentSize(int width, int height);
   void UpdateScrollOffsetAndPageScaleFactor(int x, int y, float scale);
+  void UpdateUnusedScrollOffset(int x, int y);
   void UpdatePageScaleLimits(float minimum_scale, float maximum_scale);
   void UpdateOffsetsForFullscreen(float controls_offset_y,
                                   float content_offset_y);
   void ImeUpdateAdapter(int native_ime_adapter, int text_input_type,
                         const std::string& text,
                         int selection_start, int selection_end,
                         int composition_start, int composition_end,
                         bool show_ime_if_needed);
   void SetTitle(const string16& title);
   void OnBackgroundColorChanged(SkColor color);
@@ skipping 88 matching lines @@
   ui::WindowAndroid* window_android_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentViewCoreImpl);
 };
 
 bool RegisterContentViewCore(JNIEnv* env);
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_