Add support for omnibox.onInputStarted and onInputCancelled.

chrome/browser/autocomplete/autocomplete.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 510 matching lines @@
   //
   // Once Stop() has been called, no more notifications should be sent.
   //
   // |minimal_changes| is an optimization that lets the provider do less work
   // when the |input|'s text hasn't changed.  See the body of
   // AutocompletePopupModel::StartAutocomplete().
   virtual void Start(const AutocompleteInput& input,
                      bool minimal_changes) = 0;
 
   // Called when a provider must not make any more callbacks for the current
-  // query.
+  // query. This will be called regardless of whether the provider is already
+  // done.
   virtual void Stop() {
     done_ = true;
   }
 
   // Returns the set of matches for the current query.
   const ACMatches& matches() const { return matches_; }
 
   // Returns whether the provider is done processing the query.
   bool done() const { return done_; }
 
@@ skipping 347 matching lines @@
   AutocompleteInput::Type input_type;
   // Selected index (if selected) or -1 (AutocompletePopupModel::kNoMatch).
   size_t selected_index;
   // Inline autocompleted length (if displayed).
   size_t inline_autocompleted_length;
   // Result set.
   const AutocompleteResult& result;
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_