Update instrumentation tests to use PreTestHooks for policies

components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java

Index: components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java
diff --git a/components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java b/components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java
index 60b40bd139a467abdc88342ece61ae473486b3ac..ea7290325a932eb0f5b3c6308cdfd4c23d6cf816 100644
--- a/components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java
+++ b/components/policy/android/java/src/org/chromium/policy/AbstractAppRestrictionsProvider.java
@@ -30,6 +30,12 @@
 public abstract class AbstractAppRestrictionsProvider extends PolicyProvider {
     private static final String PREFERENCE_KEY = "App Restrictions";
 
+    /**
+     * Key of a flag to be set in the cached policy bundle. If present, the cached policies will
+     * be used instead of the ones returned by the system.
+     */
+    @VisibleForTesting public static final String STICKY_CACHE_KEY = "StickyCacheForTests";
+
     private final Context mContext;
     private final SharedPreferences mSharedPreferences;
     private final BroadcastReceiver mAppRestrictionsChangedReceiver = new BroadcastReceiver() {
@@ -61,6 +67,10 @@ public AbstractAppRestrictionsProvider(Context context) {
      */
     protected abstract String getRestrictionChangeIntentAction();
 
+    protected String getPreferenceCacheKey() {
+        return getClass().getCanonicalName();
+    }
+
     /**
      * Start listening for restrictions changes. Does nothing if this is not supported by the
      * platform.
@@ -95,8 +105,12 @@ protected Bundle doInBackground(Void... params) {
 
             @Override
             protected void onPostExecute(Bundle result) {
-                cachePolicies(result);
-                notifySettingsAvailable(result);
+                if (cachedResult != null && cachedResult.getBoolean(STICKY_CACHE_KEY)) {

[aberent, 2015/10/07 11:13:02]

If the cachedResult is null then this will take the result of
getApplicationRestriction even in a test. Is this what you intend?

Do you want STICKY_CACHE_KEY to last between tests? If not, would it be better
to just use a local variable (static if necessary) to change the caching
behavior? 

[dgn, 2015/10/07 14:36:57]

As I understand it, the only way to get null would be to set the cache on a
context that's not from chrome. I'm not sure that's possible in the tests, but
it should be noticeable fairly easily in the CQ.

Currently STICKY_CACHE_KEY already doesn't last between tests and I set it only
if there is something to put in the cached policy bundle. Maybe I should enforce
it for all tests?

Instead of putting the policies in the cache I could bypass the cache with a
local variable, yes. Do you think it's better? I also tried to avoid test-only
members and the like but if it makes things less clear...

[aberent, 2015/10/15 14:12:25]

I don't like test only anything, but if you need something a test only member
seems simpler than a test only cache key.

+                    notifySettingsAvailable(cachedResult);
+                } else {
+                    cachePolicies(mSharedPreferences, result);
+                    notifySettingsAvailable(result);
+                }
             }
         }.executeOnExecutor(mExecutor);
     }
@@ -117,12 +131,12 @@ public void stopListening() {
         }
     }
 
-    private void cachePolicies(Bundle policies) {
+    private static void cachePolicies(SharedPreferences prefs, Bundle policies) {
         Parcel p = Parcel.obtain();
         p.writeBundle(policies);
         byte bytes[] = p.marshall();
         String s = Base64.encodeToString(bytes, 0);
-        SharedPreferences.Editor ed = mSharedPreferences.edit();
+        SharedPreferences.Editor ed = prefs.edit();
         ed.putString(PREFERENCE_KEY, s);
         ed.apply();
     }
@@ -169,4 +183,11 @@ protected void recordStartTimeHistogram(long startTime) {
     void setTaskExecutor(Executor testExecutor) {
         mExecutor = testExecutor;
     }
+
+    /** Context has to be the same that will be used to load the policies. */
+    @VisibleForTesting
+    public static void setCachedPoliciesForTesting(Context context, Bundle policies) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        cachePolicies(prefs, policies);
+    }
 }