Fix the handling of user gestures for external protocol handler dialogs.

chrome/browser/external_protocol/external_protocol_handler.h

Index: chrome/browser/external_protocol/external_protocol_handler.h
diff --git a/chrome/browser/external_protocol/external_protocol_handler.h b/chrome/browser/external_protocol/external_protocol_handler.h
index 7c934c5f7c6db51fe133bc4f5e2ad581836dd512..eb0057cbe76e87cde30c772a2ac6b38d4aba9a03 100644
--- a/chrome/browser/external_protocol/external_protocol_handler.h
+++ b/chrome/browser/external_protocol/external_protocol_handler.h
@@ -55,7 +55,8 @@ class ExternalProtocolHandler {
   // Must run on the UI thread.
   static void LaunchUrl(const GURL& url, int render_process_host_id,
                         int tab_contents_id) {
-      LaunchUrlWithDelegate(url, render_process_host_id, tab_contents_id, NULL);
+      LaunchUrlWithDelegate(
+          url, render_process_host_id, tab_contents_id, NULL);

[not at google - send to devlin, 2014/03/28 18:54:23]

doesn't seem like a necessary change, but "git cl format" would probably fix
that?

[meacer, 2014/03/28 19:53:11]

Yes, this remained from the previous patchset.

   }
 
   // Version of LaunchUrl allowing use of a delegate to facilitate unit
@@ -96,11 +97,23 @@ class ExternalProtocolHandler {
   // preferences for them do not already exist.
   static void PrepopulateDictionary(base::DictionaryValue* win_pref);
 
-  // Allows LaunchUrl to proceed with launching an external protocol handler.
-  // This is typically triggered by a user gesture, but is also called for
-  // each extension API function. Note that each call to LaunchUrl resets
-  // the state to false (not allowed).
-  static void PermitLaunchUrl();
+  class ScopedUserGesture {
+   public:
+     ScopedUserGesture() {
+       ExternalProtocolHandler::EnableUserGesture();
+     }
+     ~ScopedUserGesture() {
+       ExternalProtocolHandler::DisableUserGesture();

[not at google - send to devlin, 2014/03/28 18:54:23]

that's not quite right, it would break nested scopes. consider an int for
g_user_gesture or something along those lines.

I think it would be better to implement the constructor/destructor inside the
.cc file so that you can contain the state even better by not needing the
EnableUserGesture/DisableUserGesture exposed anywhere. You could access
g_user_gesture directly.

[meacer, 2014/03/28 19:53:11]

Done.

+     }
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ScopedUserGesture);
+  };
+
+ private:
+   static void EnableUserGesture();
+   static void DisableUserGesture();
+   DISALLOW_COPY_AND_ASSIGN(ExternalProtocolHandler);
 };
 
+
 #endif  // CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_HANDLER_H_