Omnibox - Make Omnibox Extensions Ignore Stop() Calls Due to User Idleness

components/omnibox/autocomplete_provider.h

Index: components/omnibox/autocomplete_provider.h
diff --git a/components/omnibox/autocomplete_provider.h b/components/omnibox/autocomplete_provider.h
index c86c274ed9f6ac8effe7671b674a1a46044979ae..3e61efd51989e719dfacb5d428663cb508b89ebb 100644
--- a/components/omnibox/autocomplete_provider.h
+++ b/components/omnibox/autocomplete_provider.h
@@ -151,7 +151,9 @@ class AutocompleteProvider
   // otherwise, starting each provider running would result in a flurry of
   // notifications).
   //
-  // Once Stop() has been called, no more notifications should be sent.
+  // Once Stop() has been called with user_inactivity_timer=false (i.e., the
+  // user did an action to cancel this input), no more notifications should
+  // be sent.

[Peter Kasting, 2015/03/05 23:27:28]

Nit: How about:

Once Stop() has been called, no more notifications should usually be sent (see
comments on Stop() below).

[Mark P, 2015/03/06 21:24:34]

Took (roughly) your suggestions.  I like removing the redundancy between
comments (which your revision does).

   //
   // |minimal_changes| is an optimization that lets the provider do less work
   // when the |input|'s text hasn't changed.  See the body of
@@ -165,11 +167,15 @@ class AutocompleteProvider
                      bool minimal_changes,
                      bool called_due_to_focus) = 0;
 
-  // Called when a provider must not make any more callbacks for the current
-  // query. This will be called regardless of whether the provider is already
-  // done.  If the provider caches any results, it should clear the cache based
-  // on the value of |clear_cached_results|.
-  virtual void Stop(bool clear_cached_results);
+  // Called with user_inactivity_timer=false (i.e., the user did an action to
+  // cancel this input) when a provider must not make any more callbacks for
+  // the current query. When called with user_inactivity_timer=true, providers
+  // should generally not make any more callbacks for the current query, though
+  // they are allowed.  Stop() will be called regardless of whether the provider
+  // is already done.  If the provider caches any results, it should clear the
+  // cache based on the value of |clear_cached_results|.

[Peter Kasting, 2015/03/05 23:27:28]

Nit: How about:

Advises the provider to stop processing.  This may be called even if the
provider is already done.  If the provider caches any results, it should clear
the cache based on the value of |clear_cached_results|.  Normally, once this is
called, the provider should not send more notifications to the controller.

If |user_inactivity_timer| is true, Stop() is being called because it's been a
long time since the user started the current query, and returning further
asynchronous results would normally just be disruptive.  Most providers should
still stop processing in this case, but continuing is legal if there's a good
reason the user is likely to want even long-delayed asynchronous results, e.g.
the user has explicitly invoked a keyword extension and the extension is still
processing the request.

[Mark P, 2015/03/06 21:24:34]

Very nice.  Done.

+  virtual void Stop(bool clear_cached_results,
+                    bool user_inactivity_timer);
 
   // Returns the enum equivalent to the name of this provider.
   // TODO(derat): Make metrics use AutocompleteProvider::Type directly, or at