[Extensions] Make Event::restrict_to_browser_context const.

extensions/browser/event_router.h

 // Copyright (c) 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.
 
 #ifndef EXTENSIONS_BROWSER_EVENT_ROUTER_H_
 #define EXTENSIONS_BROWSER_EVENT_ROUTER_H_
 
 #include <set>
 #include <string>
 #include <unordered_map>
@@ skipping 348 matching lines @@
   // correlates 1:1 with |event_name|, in some cases events will generate
   // their own names, but they cannot generate their own identifier.
   const events::HistogramValue histogram_value;
 
   // The event to dispatch.
   const std::string event_name;
 
   // Arguments to send to the event listener.
   std::unique_ptr<base::ListValue> event_args;
 
-  // If non-NULL, then the event will not be sent to other BrowserContexts
+  // If non-null, then the event will not be sent to other BrowserContexts
   // unless the extension has permission (e.g. incognito tab update -> normal
   // tab only works if extension is allowed incognito access).
-  content::BrowserContext* restrict_to_browser_context;
+  content::BrowserContext* const restrict_to_browser_context;
 
   // If not empty, the event is only sent to extensions with host permissions
   // for this url.
   GURL event_url;
 
   // Whether a user gesture triggered the event.
   EventRouter::UserGestureState user_gesture;
 
   // Extra information used to filter which events are sent to the listener.
   EventFilteringInfo filter_info;
 
   // If specified, this is called before dispatching an event to each
   // extension. The third argument is a mutable reference to event_args,
   // allowing the caller to provide different arguments depending on the
   // extension and profile. This is guaranteed to be called synchronously with
   // DispatchEvent, so callers don't need to worry about lifetime.
   //
   // NOTE: the Extension argument to this may be NULL because it's possible for
   // this event to be dispatched to non-extension processes, like WebUI.
   WillDispatchCallback will_dispatch_callback;
 
+  // TODO(lazyboy): This sets |restrict_to_browser_context| to nullptr, this
+  // will dispatch the event to unrelated profiles, not just incognito. Audit
+  // and limit usages of this constructor and introduce "include incognito"
+  // option to a constructor version for clients that need to disptach events to
+  // related browser_contexts. See https://crbug.com/726022.
   Event(events::HistogramValue histogram_value,
         const std::string& event_name,
         std::unique_ptr<base::ListValue> event_args);
 
   Event(events::HistogramValue histogram_value,
         const std::string& event_name,
         std::unique_ptr<base::ListValue> event_args,
         content::BrowserContext* restrict_to_browser_context);
 
   Event(events::HistogramValue histogram_value,
@@ skipping 21 matching lines @@
   const std::string event_name;
 
   const std::string extension_id;
   const GURL listener_url;
   content::BrowserContext* const browser_context;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EVENT_ROUTER_H_