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 d45e429af7bbcf9b56c4f4842aaf5e4ce2cb4b8c..67dbebf97132502c19bcad1db443b39b7beb0f14 100644
--- a/chrome/test/data/policy/policy_test_cases.json
+++ b/chrome/test/data/policy/policy_test_cases.json
@@ -2243,6 +2243,14 @@
   "KeyPermissions": {
   },
 
+  "HardwareAccelerationModeEnabled": {
+    "os": ["win", "linux", "mac", "chromeos", "android"],
+    "test_policy": { "HardwareAccelerationModeEnabled": false },
+    "pref_mappings": [
+      { "pref": "hardware_acceleration_mode.enabled" }

[bartfab (slow), 2015/07/01 09:16:54]

Since this pref is exposed in chrome://settings, please add a controlled setting
indicator for it and extend the test case accordingly.

[Zhenyao Mo, 2015/07/01 17:56:07]

I read the documentation and also examples in this file, but I still have no
good idea how to set up indicator_test_setup_js and indicator_selector.  Can you
give me a hand here?  The settings is Advanced Settings -> System -> Use
hardware acceleration when available.

[bartfab (slow), 2015/07/08 12:40:33]

You do not need to worry about |indicator_test_setup_js| and
|indicator_selector|. These are for special cases only where our default
mechanisms do not work. In your case, the default mechanisms should work:

1) Add a controlled-setting-indicator element to the HTML page that contains the
hardware acceleration setting and set up its attributes so that it listens for
the right pref.
2) Add one or more |indicator_tests|. They will locate the correct indicator
automatically.

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