Expose the MacViewsWebUIDialogs feature flag to chrome://flags

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 5e3c53de2fb2a644f0299b5a3ef41bdc726eaf1f..a28193dc6e29c381e3ee80e37de906a30aafdd94 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -6585,11 +6585,17 @@ Keep your key file in a safe place. You will need it to create new versions of y
         <message name="IDS_FLAGS_APP_WINDOW_CYCLING_DESCRIPTION" desc="Description of flag to enable or disable custom Cmd+` App window cycling on Mac.">
           Changes the behavior of Cmd+` when a Chrome App becomes active. When enabled, Chrome Apps will not be cycled when Cmd+` is pressed from a browser window, and browser windows will not be cycled when a Chrome App is active.
         </message>
-        <message name="IDS_FLAGS_MAC_VIEWS_DIALOGS_NAME" desc="Name of the flag to enable toolkit-views browser dialogs on Mac.">
-          Toolkit-Views Browser Dialogs.
+        <message name="IDS_FLAGS_MAC_VIEWS_NATIVE_DIALOGS_NAME" desc="Name of the flag to enable toolkit-views for native-looking browser dialogs on Mac." translateable="false">
+          Toolkit-Views Native-style Browser Dialogs.
         </message>
-        <message name="IDS_FLAGS_MAC_VIEWS_DIALOGS_DESCRIPTION" desc="Description of the flag to enable toolkit-views browser dialogs on Mac.">
-          Causes Chrome on Mac to use a toolkit-views browser dialog when available, in place of the equivalent Cocoa dialog.
+        <message name="IDS_FLAGS_MAC_VIEWS_NATIVE_DIALOGS_DESCRIPTION" desc="Description of the flag to enable toolkit-views for native-looking browser dialogs on Mac." translateable="false">
+          Use toolkit-views dialogs in place of the native Cocoa dialogs that use unaltered OSX-style buttons.
+        </message>
+        <message name="IDS_FLAGS_MAC_VIEWS_WEBUI_DIALOGS_NAME" desc="Name of the flag to enable toolkit-views for WebUI-themed browser dialogs on Mac." translateable="false">
+          Toolkit-Views WebUI-style Browser Dialogs.
+        </message>
+        <message name="IDS_FLAGS_MAC_VIEWS_WEBUI_DIALOGS_DESCRIPTION" desc="Description of the flag to enable toolkit-views for WebUI-themed browser dialogs on Mac." translateable="false">
+          Use toolkit-views dialogs in place of the native Cocoa dialogs that use square, grey, webui-style buttons.
         </message>
       </if>
       <if expr="chromeos">