Add a group policy for hardware acceleration.

chrome/test/data/policy/policy_test_cases.json

Index: chrome/test/data/policy/policy_test_cases.json
diff --git a/chrome/test/data/policy/policy_test_cases.json b/chrome/test/data/policy/policy_test_cases.json
index e3d6a20daf701d860c7d78260c2a1050381ac432..6bcdec0ba0750df49a2adec47947f94a0cb81d92 100644
--- a/chrome/test/data/policy/policy_test_cases.json
+++ b/chrome/test/data/policy/policy_test_cases.json
@@ -2253,6 +2253,20 @@
   "KeyPermissions": {
   },
 
+  "HardwareAccelerationModeEnabled": {
+    "os": ["win", "linux", "mac"],
+    "test_policy": { "HardwareAccelerationModeEnabled": true },
+    "pref_mappings": [
+      { "pref": "hardware_acceleration_mode.enabled",
+        "local_state": true,
+        "indicator_tests": [
+          { "policy": { "HardwareAccelerationModeEnabled": true } },
+          { "policy": { "HardwareAccelerationModeEnabled": false } }

[Andrew T Wilson (Slow), 2015/07/16 09:59:55]

Just curious, should we be also setting read_only: true?

[Zhenyao Mo, 2015/07/16 18:06:31]

Done.

[Zhenyao Mo, 2015/07/16 20:21:16]

OK, re-read the explanation in the template on top of this file, readonly is
used in the test where setting a policy makes another pref readonly, not the
pref that's directly connected with the policy.  So it doesn't apply here. 
Revert this change.

+        ]
+      }
+    ]
+  },
+
   "----- Chrome OS device policies ---------------------------------------": {},
 
   "DevicePolicyRefreshRate": {