Re-add snap-back behavior (Chrome side)

content/content_renderer.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': [
     '../gin/gin.gyp:gin',
     '../jingle/jingle.gyp:jingle_glue',
     '../media/media.gyp:media',
     '../net/net.gyp:net',
@@ skipping 518 matching lines @@
     'renderer/webcrypto/shared_crypto.cc',
     'renderer/webcrypto/shared_crypto.h',
     'renderer/webcrypto/webcrypto_impl.cc',
     'renderer/webcrypto/webcrypto_impl.h',
     'renderer/webcrypto/webcrypto_util.cc',
     'renderer/webcrypto/webcrypto_util.h',
     'renderer/webgraphicscontext3d_provider_impl.cc',
     'renderer/webgraphicscontext3d_provider_impl.h',
     'renderer/webpublicsuffixlist_impl.cc',
     'renderer/webpublicsuffixlist_impl.h',
+    'renderer/webscrollbarbehavior_impl_gtkoraura.cc',
+    'renderer/webscrollbarbehavior_impl_gtkoraura.h',
+    'renderer/webscrollbarbehavior_impl_mac.mm',
+    'renderer/webscrollbarbehavior_impl_mac.h',
     'renderer/websharedworker_proxy.cc',
     'renderer/websharedworker_proxy.h',
   ],
   'conditions': [
     ['notifications==0', {
       'sources!': [
         'renderer/notification_provider.cc',
         'renderer/active_notification_tracker.cc',
       ],
     }],
     ['input_speech==0', {
       'sources!': [
         'renderer/input_tag_speech_dispatcher.cc',
         'renderer/input_tag_speech_dispatcher.h',
       ]
     }],
     ['toolkit_uses_gtk == 1', {
       'dependencies': [
         '../build/linux/system.gyp:gtk',
       ],
     }],
     ['OS=="mac"', {
       'sources!': [
         'common/process_watcher_posix.cc',
+        'renderer/webscrollbarbehavior_impl_gtkoraura.cc',
+        'renderer/webscrollbarbehavior_impl_gtkoraura.h',
+      ],
+    }, {
+      'sources!': [
+        'renderer/webscrollbarbehavior_impl_mac.mm',
+        'renderer/webscrollbarbehavior_impl_mac.h',
       ],
     }],
     ['OS=="win" and win_use_allocator_shim==1', {
       'dependencies': [
           '../base/allocator/allocator.gyp:allocator',
       ],
     }],
     ['OS=="android"', {
       'sources!': [
         'renderer/accessibility/renderer_accessibility_focus_only.cc'
@@ skipping 206 matching lines @@
     }],
   ],
   'target_conditions': [
     ['OS=="android"', {
       'sources/': [
         ['include', '^renderer/render_view_linux\\.cc$'],
       ],
     }],
   ],
 }