<webview> Dialog API should get cancelled by default in stable shim c…

…ode.

When web_view_experimental.js is not present (CHANNEL_STABLE/CHANNEL_BETA), guest
dispatches 'dialog' event but never hears back from it, hanging the guest.
This CL ensures that we do not dispatch the event in
non-experimental case and deny the request immediately.

BUG=304238
Test=An app with a <webview>, the <webview> triggers a window.confirm()
  dialog. Now if experimental shim (web_view_experimental.js) is disabled
  (which is the case for stable channel), the guest would hang without
  this change. With this change, the effect is that the dialog is
  cancelled.
Tested with manually disabling experimental code from
chrome/renderer/extensions/dispatcher.cc:~1120.

Review URL: https://codereview.chromium.org/25627007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227098 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/guestview/webview/webview_guest.cc

@@ -320,6 +320,12 @@ bool WebViewGuest::RequestPermission(
       break;
     }
     case BROWSER_PLUGIN_PERMISSION_TYPE_JAVASCRIPT_DIALOG: {
+      chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+      if (channel > chrome::VersionInfo::CHANNEL_DEV) {
+        // 'dialog' API is not available in stable/beta.
+        callback.Run(false, std::string());
+        return true;
+      }
       DispatchEvent(new GuestView::Event(webview::kEventDialog,
                                          args.Pass()));
       break;