Removes the new-avatar-menu flags, enabling the feature for all users.

This CL removes the option to use the old avatar menu but doesn't fully
remove the associated code. That cleanup will happen as a follow up.

BUG=451920

Review URL: https://codereview.chromium.org/1124383004

Cr-Commit-Position: refs/heads/master@{#330775}

chrome/app/generated_resources.grd

@@ -6390,7 +6390,7 @@ Keep your key file in a safe place. You will need it to create new versions of y
       </message>
       <message name="IDS_FLAGS_ENABLE_PASSWORD_FORCE_SAVING_DESCRIPTION" desc="Description of the flag for the password manager's force-saving option.">
         Allow the user to manually enforce password saving instead of relying on password manager's heuristics.
-      </message>      
+      </message>
       <message name="IDS_FLAGS_PASSWORD_MANAGER_LINK_NAME" desc="Name of the flag to enable showing a link to account central on password settings page">
         Enable remote password management link
       </message>
@@ -14350,12 +14350,6 @@ After you create a new supervised user, you can manage their settings at any tim
       <message name="IDS_FLAGS_ENABLE_ACCOUNT_CONSISTENCY_DESCRIPTION" desc="Description for the flag to enable the account consistency between browser and cookie jar.">
         When enabled, the browser manages signing in and out of Google accounts.
       </message>
-      <message name="IDS_FLAGS_ENABLE_NEW_AVATAR_MENU_NAME" desc="Title for the flag to enable the new avatar menu.">
-        Enable the new avatar menu
-      </message>
-      <message name="IDS_FLAGS_ENABLE_NEW_AVATAR_MENU_DESCRIPTION" desc="Description for the flag to enable the new avatar menu.">
-        Enables the new avatar menu. When combined with new-profile-management, it simply shows the new profile management avatar menu. Otherwise it shows a redesigned avatar menu with the same functionality as the old one, plus a tutorial card at the top prompting the user to try out the new profile management UI.
-      </message>
 
       <message name="IDS_FLAGS_ENABLE_IFRAME_BASED_SIGNIN_NAME" desc="Title for the flag to enable iframe-based sign-in flows.">
         Enables iframe-based Chrome sign-in flows. This flag overrides --enable-web-based-signin.

chrome/browser/about_flags.cc

@@ -1554,14 +1554,6 @@ const Experiment kExperiments[] = {
     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableAccountConsistency,
                               switches::kDisableAccountConsistency)
   },
-  {
-    "enable-new-avatar-menu",
-    IDS_FLAGS_ENABLE_NEW_AVATAR_MENU_NAME,
-    IDS_FLAGS_ENABLE_NEW_AVATAR_MENU_DESCRIPTION,
-    kOsMac | kOsWin | kOsLinux,
-    ENABLE_DISABLE_VALUE_TYPE(switches::kEnableNewAvatarMenu,
-                              switches::kDisableNewAvatarMenu)
-  },
   {
     "enable-iframe-based-signin",
     IDS_FLAGS_ENABLE_IFRAME_BASED_SIGNIN_NAME,