Enable smooth scrolling on mac

build/common.gypi

 # Copyright (c) 2011 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 259 matching lines @@
           'file_manager_extension%': 0,
         }],
         
         # Enable WebUI TaskManager only on Chrome OS and Touch UI.
         ['chromeos==1 or touchui==1', {
           'webui_task_manager%': 1,
         }, {
           'webui_task_manager%': 0,
         }],
 
-        # Enable smooth scrolling for Linux and ChromeOS
-        ['OS=="linux"', {
+        # Enable smooth scrolling for Mac, Linux and ChromeOS
+        ['OS=="linux" or OS=="mac"', {
           'enable_smooth_scrolling%': 1,
         }, {
           'enable_smooth_scrolling%': 0,
         }],
       ],
     },
 
     # Copy conditionally-set variables out one scope.
     'branding%': '<(branding)',
     'buildtype%': '<(buildtype)',
@@ skipping 1720 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }