Remove the "Enable Rich Notifications" flag on ChromeOS.

chrome/browser/about_flags.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/about_flags.h"
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <set>
@@ skipping 1321 matching lines @@
     IDS_FLAGS_ENABLE_TOUCH_EDITING_NAME,
     IDS_FLAGS_ENABLE_TOUCH_EDITING_DESCRIPTION,
     kOsCrOS,
     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableTouchEditing,
                               switches::kDisableTouchEditing)
   },
   {
     "enable-rich-notifications",
     IDS_FLAGS_ENABLE_RICH_NOTIFICATIONS_NAME,
     IDS_FLAGS_ENABLE_RICH_NOTIFICATIONS_DESCRIPTION,
-    kOsWin | kOsCrOS | kOsMac,
+    kOsWin | kOsMac,
     ENABLE_DISABLE_VALUE_TYPE(
         message_center::switches::kEnableRichNotifications,
         message_center::switches::kDisableRichNotifications)
   },
   {
     "enable-sync-synced-notifications",
     IDS_FLAGS_ENABLE_SYNCED_NOTIFICATIONS_NAME,
     IDS_FLAGS_ENABLE_SYNCED_NOTIFICATIONS_DESCRIPTION,
     kOsDesktop,
     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableSyncSyncedNotifications,
@@ skipping 718 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags