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..3050811011a5cdc8bb78e954e2c6ca5649cfb6c7 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 +265,21 @@ 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: Not every place where HTML can run has a TabContentsWrapper. This
+  // class is *only* used in a visible, actual, tab inside a browser. Examples
+  // of things that do not have tab wrappers include:
+  // - Extension background pages and popup bubbles
+  // - HTML notification bubbles
+  // - Screensavers on Chrome OS
+  // - Other random places we decide to display HTML over time
+  //
+  // Consider carefully whether your feature is something that makes sense only
+  // when a tab is displayed, or could make sense in other cases we use HTML. It
+  // may makes sense to push down into WebContents and make configurable, or at
+  // least to make easy for other WebContents hosts to include and support.

[Avi (use Gerrit), 2012/05/25 20:44:56]

Move the comment up to be a class comment, line 76 or so.

[benjhayden, 2012/05/25 21:00:50]

Done.

 
   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_;