Refactor GestureNavigation to eliminate code redundancy

content/content_browser.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../device/vibration/vibration.gyp:device_vibration',
     '../device/vibration/vibration.gyp:device_vibration_mojo_bindings',
@@ skipping 1394 matching lines @@
       'browser/transition_request_manager.h',
       'browser/udev_linux.cc',
       'browser/udev_linux.h',
       'browser/user_metrics.cc',
       'browser/utility_process_host_impl.cc',
       'browser/utility_process_host_impl.h',
       'browser/web_contents/aura/gesture_nav_simple.cc',
       'browser/web_contents/aura/gesture_nav_simple.h',
       'browser/web_contents/aura/overscroll_navigation_overlay.cc',
       'browser/web_contents/aura/overscroll_navigation_overlay.h',
+      'browser/web_contents/aura/overscroll_window_animation.cc',
+      'browser/web_contents/aura/overscroll_window_animation.h',
+      'browser/web_contents/aura/overscroll_window_delegate.cc',
+      'browser/web_contents/aura/overscroll_window_delegate.h',
       'browser/web_contents/aura/shadow_layer_delegate.cc',
       'browser/web_contents/aura/shadow_layer_delegate.h',
       'browser/web_contents/aura/window_slider.cc',
       'browser/web_contents/aura/window_slider.h',
       'browser/web_contents/touch_editable_impl_aura.cc',
       'browser/web_contents/touch_editable_impl_aura.h',
       'browser/web_contents/web_contents_android.cc',
       'browser/web_contents/web_contents_android.h',
       'browser/web_contents/web_contents_impl.cc',
       'browser/web_contents/web_contents_impl.h',
@@ skipping 546 matching lines @@
         'browser/media/media_web_contents_observer.h',
       ],
     }],
     ['OS == "linux" and use_openssl==1', {
       'dependencies': [
         '../third_party/boringssl/boringssl.gyp:boringssl',
       ],
     }],
   ],
 }