Enable GPU by default

Content Shell cannot run without GPU enabled. So enable GPU by default
in emulator.

BUG=


Review URL: https://chromiumcodereview.appspot.com/11148036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@162334 0039d316-1c4b-4281-b951-d872f2087c98

build/android/emulator.py

@@ -221,6 +221,8 @@ class Emulator(object):
         # The default /data size is 64M.
         # That's not enough for 8 unit test bundles and their data.
         '-partition-size', '512',
+        # Enable GPU by default.
+        '-gpu', 'on',
         # Use a familiar name and port.
         '-avd', self.avd,
         '-port', str(port)]