Reland of Change the update_client task runner behavior to continue on shutdown.

components/update_client/update_client.h

 // Copyright 2015 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 COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ skipping 122 matching lines @@
 class DictionaryValue;
 class FilePath;
 }
 
 namespace update_client {
 
 class Configurator;
 struct CrxUpdateItem;
 
 enum Error {
+  ERROR_UPDATE_INVALID_ARGUMENT = -1,
   ERROR_UPDATE_IN_PROGRESS = 1,
+  ERROR_UPDATE_CANCELED = 2,
 };
 
 // Defines an interface for a generic CRX installer.
 class CrxInstaller : public base::RefCountedThreadSafe<CrxInstaller> {
  public:
   // Called on the main thread when there was a problem unpacking or
   // verifying the CRX. |error| is a non-zero value which is only meaningful
   // to the caller.
   virtual void OnUpdateError(int error) = 0;
 
@@ skipping 135 matching lines @@
 
   // Returns status details about a CRX update. The function returns true in
   // case of success and false in case of errors, such as |id| was
   // invalid or not known.
   virtual bool GetCrxUpdateState(const std::string& id,
                                  CrxUpdateItem* update_item) const = 0;
 
   // Returns true if the |id| is found in any running task.
   virtual bool IsUpdating(const std::string& id) const = 0;
 
+  // Cancels the queued updates and makes a best effort to stop updates in
+  // progress as soon as possible. Some updates may not be stopped, in which
+  // case, the updates will run to completion. Calling this function has no
+  // effect if updates are not currently executed or queued up.
+  virtual void Stop() = 0;
+
  protected:
   friend class base::RefCounted<UpdateClient>;
 
   virtual ~UpdateClient() {}
 };
 
 // Creates an instance of the update client.
 scoped_refptr<UpdateClient> UpdateClientFactory(
     const scoped_refptr<Configurator>& config);
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_