Fix crashes in DownloadRequestLimiter when extension popups/bubbles initiate downloads automatically

chrome/browser/download/download_request_limiter.h

Index: chrome/browser/download/download_request_limiter.h
diff --git a/chrome/browser/download/download_request_limiter.h b/chrome/browser/download/download_request_limiter.h
index 457de30e5caa4ee737c9855c5803ac1396c9b362..c0e1fae74745b276bbc86c90a7e8c6281448b414 100644
--- a/chrome/browser/download/download_request_limiter.h
+++ b/chrome/browser/download/download_request_limiter.h
@@ -17,6 +17,7 @@
 #include "content/public/browser/notification_registrar.h"
 
 class DownloadRequestInfoBarDelegate;
+class DownloadRequestLimiterObserver;
 class TabContentsWrapper;
 
 namespace content {
@@ -224,7 +225,7 @@ class DownloadRequestLimiter
 
   // Does the work of updating the download status on the UI thread and
   // potentially prompting the user.
-  void CanDownloadImpl(TabContentsWrapper* originating_tab,
+  void CanDownloadImpl(content::WebContents* originating_contents,
                        int request_id,
                        const std::string& request_method,
                        const Callback& callback);
@@ -238,6 +239,9 @@ class DownloadRequestLimiter
   // ALLOW_ONE_DOWNLOAD.
   void Remove(TabDownloadState* state);
 
+  void RemoveObserver(content::WebContents* web_contents,
+                      DownloadRequestLimiterObserver* observer);
+
   // Maps from tab to download state. The download state for a tab only exists
   // if the state is other than ALLOW_ONE_DOWNLOAD. Similarly once the state
   // transitions from anything but ALLOW_ONE_DOWNLOAD back to ALLOW_ONE_DOWNLOAD
@@ -245,6 +249,10 @@ class DownloadRequestLimiter
   typedef std::map<content::NavigationController*, TabDownloadState*> StateMap;
   StateMap state_map_;
 
+  typedef std::map<content::WebContents*, DownloadRequestLimiterObserver*>
+    ObserverMap;
+  ObserverMap observer_map_;
+
   static TestingDelegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadRequestLimiter);