Turn the utility process image decoder into a Mojo service.

chrome/browser/image_decoder.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_IMAGE_DECODER_H_
 #define CHROME_BROWSER_IMAGE_DECODER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "content/public/browser/utility_process_host_client.h"
+#include "services/image_decoder/public/interfaces/image_decoder.mojom.h"
 
 class SkBitmap;
 
 // Decodes an image in a sandboxed process.
-class ImageDecoder : public content::UtilityProcessHostClient {
+class ImageDecoder : public content::UtilityProcessHostClient,
+                     public mojo::ErrorHandler {
  public:
   class Delegate {
    public:
     // Called when image is decoded.
     // |decoder| is used to identify the image in case of decoding several
     // images simultaneously.
     virtual void OnImageDecoded(const ImageDecoder* decoder,
                                 const SkBitmap& decoded_image) = 0;
 
     // Called when decoding image failed. Delegate can do some cleanup in
@@ skipping 28 matching lines @@
   void set_delegate(Delegate* delegate) { delegate_ = delegate; }
   void set_shrink_to_fit(bool shrink_to_fit) { shrink_to_fit_ = shrink_to_fit; }
 
  private:
   // It's a reference counted object, so destructor is private.
   ~ImageDecoder() override;
 
   // Overidden from UtilityProcessHostClient:
   bool OnMessageReceived(const IPC::Message& message) override;
 
+  // Overidden from mojo::ErrorHandler:
+  void OnConnectionError() override;
+
   // IPC message handlers.
   void OnDecodeImageSucceeded(const SkBitmap& decoded_image);
   void OnDecodeImageFailed();
 
   // Launches sandboxed process that will decode the image.
   void DecodeImageInSandbox(const std::vector<unsigned char>& image_data);
 
+  // Mojo RPC callback.
+  void OnDecodeImageDone(bool success, skia::BitmapPtr image);

[sky, 2015/04/01 15:00:45]

Do we need to distinguish between failure and an empty image? I'm wondering if
we can get away without the success arg. That you only notify
OnDecodeImageSucceeded on success and non-empty image seems to indicate you
don't know the success boolean.

[Anand Mistry (off Chromium), 2015/04/02 04:29:45]

Done.

+
   Delegate* delegate_;
   std::vector<unsigned char> image_data_;
   const ImageCodec image_codec_;
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
-  bool shrink_to_fit_; // if needed for IPC msg size limit
+  bool shrink_to_fit_;  // if needed for IPC msg size limit
+  services::ImageDecoderPtr decoder_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
 };
 
 #endif  // CHROME_BROWSER_IMAGE_DECODER_H_