Monitor Profile destruction from ChromeExtensionMessageFilter.

chrome/browser/renderer_host/chrome_extension_message_filter.h

Index: chrome/browser/renderer_host/chrome_extension_message_filter.h
diff --git a/chrome/browser/renderer_host/chrome_extension_message_filter.h b/chrome/browser/renderer_host/chrome_extension_message_filter.h
index 57cd9270d4c147eb52b74c88235a883f8c130037..4a3f341bceda0210b5b83a1bc9f75b2041768282 100644
--- a/chrome/browser/renderer_host/chrome_extension_message_filter.h
+++ b/chrome/browser/renderer_host/chrome_extension_message_filter.h
@@ -9,6 +9,8 @@
 
 #include "base/sequenced_task_runner_helpers.h"
 #include "content/public/browser/browser_message_filter.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
 class GURL;
 class Profile;
@@ -26,7 +28,8 @@ class InfoMap;
 
 // This class filters out incoming Chrome-specific IPC messages from the
 // extension process on the IPC thread.
-class ChromeExtensionMessageFilter : public content::BrowserMessageFilter {
+class ChromeExtensionMessageFilter : public content::BrowserMessageFilter,
+                                     public content::NotificationObserver {
  public:
   ChromeExtensionMessageFilter(int render_process_id, Profile* profile);
 
@@ -35,6 +38,7 @@ class ChromeExtensionMessageFilter : public content::BrowserMessageFilter {
   virtual void OverrideThreadForMessage(
       const IPC::Message& message,
       content::BrowserThread::ID* thread) OVERRIDE;
+  virtual void OnDestruct() const OVERRIDE;
 
  private:
   friend class content::BrowserThread;
@@ -97,14 +101,23 @@ class ChromeExtensionMessageFilter : public content::BrowserMessageFilter {
       const std::string& extension_id,
       const ExtensionHostMsg_APIActionOrEvent_Params& params);
 
+  // content::NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
   const int render_process_id_;
 
   // The Profile associated with our renderer process.  This should only be
-  // accessed on the UI thread!
+  // accessed on the UI thread! Furthermore since this class is refcounted it
+  // may outlive |profile_|, so make sure to NULL check if in doubt; async
+  // calls and the like.
   Profile* profile_;
 
   scoped_refptr<extensions::InfoMap> extension_info_map_;
 
+  content::NotificationRegistrar notification_registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeExtensionMessageFilter);
 };