Support WebP images in the IOSImageDecoderImpl

ios/chrome/browser/suggestions/ios_image_decoder_impl.h

 // Copyright 2016 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 IOS_CHROME_BROWSER_SUGGESTIONS_IOS_IMAGE_DECODER_IMPL_H_
 #define IOS_CHROME_BROWSER_SUGGESTIONS_IOS_IMAGE_DECODER_IMPL_H_
 
+#include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "components/image_fetcher/image_decoder.h"
 
+@class NSData;
+
+namespace base {
+class TaskRunner;
+}
+
 namespace suggestions {
 
 class IOSImageDecoderImpl : public image_fetcher::ImageDecoder {
  public:
-  IOSImageDecoderImpl();
+  explicit IOSImageDecoderImpl(
+      const scoped_refptr<base::TaskRunner>& task_runner);
   ~IOSImageDecoderImpl() override;
 
   void DecodeImage(
       const std::string& image_data,
       const image_fetcher::ImageDecodedCallback& callback) override;
 
  private:
+  void CreateUIImageAndRunCallback(
+      const image_fetcher::ImageDecodedCallback& callback,
+      base::scoped_nsobject<NSData> data);

[noyau (Ping after 24h), 2016/09/09 10:18:04]

This private use scoped_nsobject has the unfortunate side effect of polluting
the factory with objectiveC. It's kind of a bummer.

Have you considered moving the class in the mm file and only provide a function
here of the form

image_fetcher::ImageDecoder createIOSImageDecoder(taskrunner);

[vitaliii, 2016/09/09 13:03:41]

No, I have not, but that is a great idea (though quite unusual to me). Done.

+
+  // The task runner used to decode images if necessary.
+  const scoped_refptr<base::TaskRunner> task_runner_;
+
+  // The WeakPtrFactory is used to cancel callbacks if ImageFetcher is destroyed
+  // during WebP decoding.
+  base::WeakPtrFactory<IOSImageDecoderImpl> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(IOSImageDecoderImpl);
 };
 
 }  // namespace suggestions
 
 #endif  // IOS_CHROME_BROWSER_SUGGESTIONS_IOS_IMAGE_DECODER_IMPL_H_