Adds about:user-actions page.

chrome/browser/ui/webui/user_actions/user_actions_ui_handler.cc

Index: chrome/browser/ui/webui/user_actions/user_actions_ui_handler.cc
diff --git a/chrome/browser/ui/webui/user_actions/user_actions_ui_handler.cc b/chrome/browser/ui/webui/user_actions/user_actions_ui_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..461a0806045d1228d1c9c038ff2ce080ec15d747
--- /dev/null
+++ b/chrome/browser/ui/webui/user_actions/user_actions_ui_handler.cc
@@ -0,0 +1,37 @@
+// Copyright 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/ui/webui/user_actions/user_actions_ui_handler.h"
+
+#include "base/logging.h"
+#include "base/values.h"
+#include "content/public/browser/notification_details.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
+#include "content/public/browser/notification_types.h"
+#include "content/public/browser/web_ui.h"
+
+UserActionsUIHandler::UserActionsUIHandler() : NotificationObserver() {
+  registrar_.Add(this,
+                 content::NOTIFICATION_USER_ACTION,
+                 content::NotificationService::AllSources());
+}
+
+UserActionsUIHandler::~UserActionsUIHandler() {
+  // No need to explicitly unregister ourselves--it's done automatically

[Evan Stade, 2012/11/20 23:09:57]

this comment is unecessary imo

[Mark P, 2012/11/20 23:45:41]

I found the behavior confusing/surprising; I'd rather keep it.

[Evan Stade, 2012/11/20 23:59:16]

this behavior is 99% of the reason registrar_ exists, and its usage is extremely
prevalent in chrome code. There are many instances of scoping classes in chrome
code: scoped_ptr, WeakPtrFactory, PrefChangeRegistrar, to name a few. If we
documented every use of every one of these objects, the readability of the
codebase would be diminished rather than improved.

[Mark P, 2012/11/21 00:18:14]

Okay.  Good argument.  I haven't look widely through the code base to know how
familiar are most devs with these things.

Done.

+  // when registrar_ is deleted.
+}
+
+void UserActionsUIHandler::Observe(
+    int type,
+    const content::NotificationSource& source,
+    const content::NotificationDetails& details) {
+  DCHECK_EQ(type, content::NOTIFICATION_USER_ACTION);
+  base::StringValue user_action_name(
+      *content::Details<const char*>(details).ptr());
+  web_ui()->CallJavascriptFunction("userActions.observeUserAction",
+                                   user_action_name);
+}
+
+void UserActionsUIHandler::RegisterMessages() {}