Enable accelerated WebKit compositor for Aura.

This allows the use of the WebKit compositor for Aura on Linux. It reuses the same display path as TOUCH_UI.

BUG=none
TEST=build GYP_DEFINES="use_aura" on Linux; go to http://www.webkit.org/blog-files/3d-transforms/poster-circle.html

Review URL: http://codereview.chromium.org/8241012

git-svn-id: http://src.chromium.org/svn/trunk/src/build@105323 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -327,6 +327,14 @@
           'proprietary_codecs%': 1,
           'enable_webrtc%': 0,
         }],
+
+        # Use GPU accelerated cross process image transport by default
+        # on TOUCH_UI and linux builds with the Aura window manager
+        ['views_compositor==1 and OS=="linux"', {
+          'views_gpu_image_transport%': 1,
+        }, {
+          'views_gpu_image_transport%': 0,
+        }],
       ],
     },
 
@@ -339,6 +347,7 @@
     'toolkit_views%': '<(toolkit_views)',
     'use_only_pure_views%': '<(use_only_pure_views)',
     'views_compositor%': '<(views_compositor)',
+    'views_gpu_image_transport%': '<(views_gpu_image_transport)',
     'use_aura%': '<(use_aura)',
     'use_openssl%': '<(use_openssl)',
     'use_nss%': '<(use_nss)',
@@ -937,6 +946,9 @@
       ['views_compositor==1', {
         'defines': ['VIEWS_COMPOSITOR=1'],
       }],
+      ['views_gpu_image_transport==1', {
+        'defines': ['UI_COMPOSITOR_IMAGE_TRANSPORT'],
+      }],
       ['use_aura==1', {
         'defines': ['USE_AURA=1'],
       }],