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

chrome/browser/ui/tab_contents/tab_contents_wrapper.h

Index: chrome/browser/ui/tab_contents/tab_contents_wrapper.h
diff --git a/chrome/browser/ui/tab_contents/tab_contents_wrapper.h b/chrome/browser/ui/tab_contents/tab_contents_wrapper.h
index 3fc5e14ef66cd57737255cc285abaf671cf706b4..00ef34bd71a0d3bc64b0ee73c8af887b3a4df379 100644
--- a/chrome/browser/ui/tab_contents/tab_contents_wrapper.h
+++ b/chrome/browser/ui/tab_contents/tab_contents_wrapper.h
@@ -22,7 +22,6 @@ class BlockedContentTabHelper;
 class BookmarkTabHelper;
 class ConstrainedWindowTabHelper;
 class CoreTabHelper;
-class DownloadRequestLimiterObserver;
 class ExtensionTabHelper;
 class ExternalProtocolObserver;
 class FaviconTabHelper;
@@ -266,9 +265,11 @@ class TabContentsWrapper : public content::WebContentsObserver {
   // Per-tab observers ---------------------------------------------------------
   // (These provide no API for callers; objects that need to exist 1:1 with tabs
   // and silently do their thing live here.)
+  // WARNING: There is no TabContentsWrapper for extension popups/bubbles and
+  // other raw WebContents. If you want anything to happen for both tabs and raw
+  // WebContents, don't put it here!
 
   scoped_ptr<AlternateErrorPageTabObserver> alternate_error_page_tab_observer_;
-  scoped_ptr<DownloadRequestLimiterObserver> download_request_limiter_observer_;
   scoped_ptr<extensions::WebNavigationTabObserver> webnavigation_observer_;
   scoped_ptr<ExternalProtocolObserver> external_protocol_observer_;
   scoped_ptr<OmniboxSearchHint> omnibox_search_hint_;