Adds gyp switch that turns on views on Linux. This currently doesn't

do anything else, but it will eventually.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/113304

git-svn-id: http://src.chromium.org/svn/trunk/src/build@15917 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -52,6 +52,11 @@
 
     # The architecture that we're building on.
     'target_arch%': 'ia32',
+
+    # By default linux does not use views. To turn on views in Linux
+    # set the variable GYP_DEFINES to "toolkit_views=1", or modify
+    # ~/.gyp/include.gypi .
+    'toolkit_views%': 0,
   },
   'target_defaults': {
     'conditions': [
@@ -60,6 +65,9 @@
       }, {  # else: branding!="Chrome"
         'defines': ['CHROMIUM_BUILD'],
       }],
+      ['toolkit_views=="1"', {
+        'defines': ['TOOLKIT_VIEWS=1'],
+      }],
       ['coverage!=0', {
         'conditions': [
           ['OS=="mac"', {