Remove Media Router preferences from incognito whitelist.

Media Router preferences are removed from the persistent storage
list for incognito mode.
After this CL, if these preferences are changed from incognito mode,
they are only stored in memory and won't affect user profile.

Bug: 861722
Change-Id: Ice965ba421945c6408b6c13b248acafe4181c76f
Reviewed-on: https://chromium-review.googlesource.com/1179147
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584365}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -547,11 +547,6 @@ const char* const kTemporaryIncognitoWhitelist[] = {
     prefs::kSystemTimezoneAutomaticDetectionPolicy,
 #endif  // defined(OS_CHROMEOS)
 
-    prefs::kEnableMediaRouter,
-#if !defined(OS_ANDROID)
-    prefs::kShowCastIconInToolbar,
-#endif  // !defined(OS_ANDROID)
-
 #if !defined(OS_ANDROID)
 #if !defined(OS_CHROMEOS)
     prefs::kRelaunchNotification,
@@ -617,12 +612,6 @@ const char* const kTemporaryIncognitoWhitelist[] = {
     prefs::kLatestVersionWhenClickedUpdateMenuItem,
 #endif
 
-    prefs::kMediaRouterCloudServicesPrefSet,
-    prefs::kMediaRouterEnableCloudServices,
-    prefs::kMediaRouterFirstRunFlowAcknowledged,
-    prefs::kMediaRouterMediaRemotingEnabled,
-    // prefs::kMediaRouterTabMirroringSources,
-
     prefs::kOriginTrialPublicKey, prefs::kOriginTrialDisabledFeatures,
     prefs::kOriginTrialDisabledTokens,