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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_
      6 #define EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_
      7 
      8 #include "content/public/browser/browser_thread.h"
      9 #include "extensions/browser/extension_function.h"
     10 
     11 namespace extensions {
     12 
     13 // AsyncApiFunction provides convenient thread management for APIs that need to
     14 // do essentially all their work on a thread other than the UI thread.
     15 class AsyncApiFunction : public AsyncExtensionFunction {
     16  protected:
     17   AsyncApiFunction();
     18   virtual ~AsyncApiFunction();
     19 
     20   // Like Prepare(). A useful place to put common work in an ApiFunction
     21   // superclass that multiple API functions want to share.
     22   virtual bool PrePrepare();
     23 
     24   // Set up for work (e.g., validate arguments). Guaranteed to happen on UI
     25   // thread.
     26   virtual bool Prepare() = 0;
     27 
     28   // Do actual work. Guaranteed to happen on the thread specified in
     29   // work_thread_id_.
     30   virtual void Work();
     31 
     32   // Start the asynchronous work. Guraranteed to happen on requested thread.
     33   virtual void AsyncWorkStart();
     34 
     35   // Notify AsyncIOApiFunction that the work is completed
     36   void AsyncWorkCompleted();
     37 
     38   // Respond. Guaranteed to happen on UI thread.
     39   virtual bool Respond() = 0;
     40 
     41   // ExtensionFunction::RunAsync()
     42   virtual bool RunAsync() OVERRIDE;
     43 
     44  protected:
     45   content::BrowserThread::ID work_thread_id() const { return work_thread_id_; }
     46   void set_work_thread_id(content::BrowserThread::ID work_thread_id) {
     47     work_thread_id_ = work_thread_id;
     48   }
     49 
     50  private:
     51   void WorkOnWorkThread();
     52   void RespondOnUIThread();
     53 
     54   // If you don't want your Work() method to happen on the IO thread, then set
     55   // this to the thread that you do want, preferably in Prepare().
     56   content::BrowserThread::ID work_thread_id_;
     57 };
     58 
     59 }  // namespace extensions
     60 
     61 #endif  // EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_
     62