Add support for GYP_DEFINES aura_wm=1 which also defines views_compositor=1.

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 24 matching lines @@
           # Disable touch support by default.
           'touchui%': 0,
 
           # Disable webui dialog replacements for native dialogs by default.
           # TODO(flackr): Change this to a runtime flag triggered by
           #     --pure-views so that these dialogs can be easily tested. 
           'webui_dialogs%': 0,
 
           # Whether the compositor is enabled on views.
           'views_compositor%': 0,
+          
+          # Whether or not we are building with the Aura window manager.
+          'aura_wm%': 0,
         },
         # Copy conditionally-set variables out one scope.
         'chromeos%': '<(chromeos)',
         'toolkit_uses_pure_views%': '<(toolkit_uses_pure_views)',
         'touchui%': '<(touchui)',
         'webui_dialogs%': '<(webui_dialogs)',
         'views_compositor%': '<(views_compositor)',
+        'aura_wm%': '<(aura_wm)',
 
         # Compute the architecture that we're building on.
         'conditions': [
           [ 'OS=="win" or OS=="mac"', {
             'host_arch%': 'ia32',
           }, {
             # This handles the Unix platforms for which there is some support.
             # Anything else gets passed through, which probably won't work very
             # well; such hosts should pass an explicit target_arch to gyp.
             'host_arch%':
@@ skipping 12 matching lines @@
           ['touchui==1', {
             'toolkit_uses_pure_views%': 1,
           }, {
             'toolkit_uses_pure_views%': 0,
           }],
 
           # Use WebUI dialogs in TouchUI builds.
           ['touchui==1', {
             'webui_dialogs%': 1,
           }],
+          
+          # Use the views compositor when using the Aura window manager.
+          ['aura_wm==1', {
+            'views_compositor%': 1,
+          }],
         ],
       },
 
       # Copy conditionally-set variables out one scope.
       'chromeos%': '<(chromeos)',
       'touchui%': '<(touchui)',
       'webui_dialogs%': '<(webui_dialogs)',
       'host_arch%': '<(host_arch)',
       'toolkit_views%': '<(toolkit_views)',
       'toolkit_uses_pure_views%': '<(toolkit_uses_pure_views)',
       'views_compositor%': '<(views_compositor)',
+      'aura_wm%': '<(aura_wm)',
 
       # We used to provide a variable for changing how libraries were built.
       # This variable remains until we can clean up all the users.
       # This needs to be one nested variables dict in so that dependent
       # gyp files can make use of it in their outer variables.  (Yikes!)
       # http://code.google.com/p/chromium/issues/detail?id=83308
       'library%': 'static_library',
 
       # Override branding to select the desired branding flavor.
       'branding%': 'Chromium',
@@ skipping 173 matching lines @@
 
     # Copy conditionally-set variables out one scope.
     'branding%': '<(branding)',
     'buildtype%': '<(buildtype)',
     'target_arch%': '<(target_arch)',
     'host_arch%': '<(host_arch)',
     'library%': 'static_library',
     'toolkit_views%': '<(toolkit_views)',
     'toolkit_uses_pure_views%': '<(toolkit_uses_pure_views)',
     'views_compositor%': '<(views_compositor)',
+    'aura_wm%': '<(aura_wm)',
     'os_posix%': '<(os_posix)',
     'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
     'use_skia%': '<(use_skia)',
     'use_x11%': '<(use_x11)',
     'use_gnome_keyring%': '<(use_gnome_keyring)',
     'linux_fpic%': '<(linux_fpic)',
     'enable_flapper_hacks%': '<(enable_flapper_hacks)',
     'chromeos%': '<(chromeos)',
     'touchui%': '<(touchui)',
     'webui_dialogs%': '<(webui_dialogs)',
@@ skipping 470 matching lines @@
       }],
       ['toolkit_views==1', {
         'defines': ['TOOLKIT_VIEWS=1'],
       }],
       ['toolkit_uses_pure_views==1', {
         'defines': ['TOOLKIT_USES_PURE_VIEWS=1'],
       }],
       ['views_compositor==1', {
         'defines': ['VIEWS_COMPOSITOR=1'],
       }],
+      ['aura_wm==1', {
+        'defines': ['AURA_WM=1'],
+      }],
       ['chromeos==1', {
         'defines': ['OS_CHROMEOS=1'],
       }],
       ['touchui==1', {
         'defines': ['TOUCH_UI=1'],
       }],
       ['use_wayland==1', {
         'defines': ['USE_WAYLAND=1', 'WL_EGL_PLATFORM=1'],
       }],
       ['file_manager_extension==1', {
@@ skipping 1179 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',
   },
 }