autocomplete: Extract AutocompleteResult from autocomplete.*.

chrome/browser/autocomplete/autocomplete_controller.h

 // Copyright (c) 2012 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_CONTROLLER_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_CONTROLLER_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/string16.h"
 #include "base/timer.h"
 #include "chrome/browser/autocomplete/autocomplete.h"
 #include "chrome/browser/autocomplete/autocomplete_provider_listener.h"
+#include "chrome/browser/autocomplete/autocomplete_result.h"
 #include "chrome/browser/autocomplete/autocomplete_types.h"
 
 class AutocompleteControllerDelegate;
 class KeywordProvider;
 class Profile;
 class SearchProvider;
 
+// The AutocompleteController is the center of the autocomplete system.  A
+// class creates an instance of the controller, which in turn creates a set of
+// AutocompleteProviders to serve it.  The owning class can ask the controller
+// to Start() a query; the controller in turn passes this call down to the
+// providers, each of which keeps track of its own matches and whether it has
+// finished processing the query.  When a provider gets more matches or finishes
+// processing, it notifies the controller, which merges the combined matches
+// together and makes the result available to interested observers.
+//
+// The owner may also cancel the current query by calling Stop(), which the
+// controller will in turn communicate to all the providers.  No callbacks will
+// happen after a request has been stopped.
+//
+// IMPORTANT: There is NO THREAD SAFETY built into this portion of the
+// autocomplete system.  All calls to and from the AutocompleteController should
+// happen on the same thread.  AutocompleteProviders are responsible for doing
+// their own thread management when they need to return matches asynchronously.
+//
 // The coordinator for autocomplete queries, responsible for combining the
 // matches from a series of providers into one AutocompleteResult.
 class AutocompleteController : public AutocompleteProviderListener {
  public:
   // Used to indicate an index that is not selected in a call to Update().
   static const int kNoItemSelected;
 
   // Normally, you will call the first constructor.  Unit tests can use the
   // second to set the providers to some known testing providers.  The default
   // providers will be overridden and the controller will take ownership of the
@@ skipping 153 matching lines @@
   // Are we in Start()? This is used to avoid updating |result_| and sending
   // notifications until Start() has been invoked on all providers.
   bool in_start_;
 
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(AutocompleteController);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_CONTROLLER_H_