Create the IOSImageDataFetcherWrapper

components/image_fetcher/ios/ios_image_data_fetcher_wrapper.mm

+// Copyright 2017 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.
+
+#import "components/image_fetcher/ios/ios_image_data_fetcher_wrapper.h"
+
+#import "base/mac/bind_objc_block.h"
+#import "base/mac/scoped_nsobject.h"
+#include "base/memory/ptr_util.h"
+#include "base/task_runner.h"
+#include "base/task_runner_util.h"
+#import "ios/web/public/image_fetcher/webp_decoder.h"
+#include "net/http/http_response_headers.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+#include "url/url_constants.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+#pragma mark - WebpDecoderDelegate
+
+namespace {
+
+class WebpDecoderDelegate : public webp_transcode::WebpDecoder::Delegate {
+ public:
+  WebpDecoderDelegate() = default;
+
+  NSData* data() const { return decoded_image_; }
+
+  // WebpDecoder::Delegate methods
+  void OnFinishedDecoding(bool success) override {
+    if (!success)
+      decoded_image_ = nil;
+  }
+  void SetImageFeatures(
+      size_t total_size,
+      webp_transcode::WebpDecoder::DecodedImageFormat format) override {
+    decoded_image_ = [[NSMutableData alloc] initWithCapacity:total_size];
+  }
+  void OnDataDecoded(NSData* data) override {
+    DCHECK(decoded_image_);
+    [decoded_image_ appendData:data];
+  }
+
+ private:
+  ~WebpDecoderDelegate() override {}

[sdefresne, 2017/02/02 10:42:05]

nit: use "= default" here too for consistency

[gambard, 2017/02/02 11:57:02]

Done.

+  NSMutableData* decoded_image_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebpDecoderDelegate);
+};
+
+// Content-type header for WebP images.
+const char kWEBPFirstMagicPattern[] = "RIFF";
+const char kWEBPSecondMagicPattern[] = "WEBP";
+
+// Returns a NSData object containing the decoded image.
+// Returns nil in case of failure.
+NSData* DecodeWebpImage(NSData* webp_image) {
+  scoped_refptr<WebpDecoderDelegate> delegate(new WebpDecoderDelegate);
+  scoped_refptr<webp_transcode::WebpDecoder> decoder(
+      new webp_transcode::WebpDecoder(delegate.get()));
+  decoder->OnDataReceived(webp_image);
+  DLOG_IF(ERROR, !delegate->data()) << "WebP image decoding failed.";
+  return delegate->data();
+}
+
+}  // namespace
+
+#pragma mark - IOSImageDataFetcherWrapper
+
+namespace image_fetcher {
+
+IOSImageDataFetcherWrapper::IOSImageDataFetcherWrapper(
+    net::URLRequestContextGetter* url_request_context_getter,
+    const scoped_refptr<base::TaskRunner>& task_runner)
+    : task_runner_(task_runner),
+      image_data_fetcher_(url_request_context_getter) {
+  DCHECK(task_runner_.get());
+}
+
+IOSImageDataFetcherWrapper::~IOSImageDataFetcherWrapper() {}
+
+void IOSImageDataFetcherWrapper::FetchImageDataWebpDecoded(
+    const GURL& image_url,
+    IOSImageDataFetcherCallback callback) {
+  DCHECK(callback);
+
+  scoped_refptr<base::TaskRunner> task_runner = task_runner_;
+  ImageDataFetcher::ImageDataFetcherCallback local_callback =
+      base::BindBlockArc(^(const std::string& image_data) {
+        // Create a NSData from the returned data and notify the callback.
+        NSData* data =
+            [NSData dataWithBytes:image_data.data() length:image_data.size()];
+
+        if (data.length < 12 ||
+            image_data.compare(0, 4, kWEBPFirstMagicPattern) != 0 ||
+            image_data.compare(8, 4, kWEBPSecondMagicPattern) != 0) {
+          callback(data);
+          return;
+        }
+
+        // The image is a webp image.
+        base::PostTaskAndReplyWithResult(task_runner.get(), FROM_HERE,
+                                         base::Bind(&DecodeWebpImage, data),
+                                         base::BindBlockArc(callback));
+      });
+  image_data_fetcher_.FetchImageData(image_url, local_callback);
+}
+
+void IOSImageDataFetcherWrapper::SetDataUseServiceName(
+    DataUseServiceName data_use_service_name) {
+  image_data_fetcher_.SetDataUseServiceName(data_use_service_name);
+}
+
+}  // namespace image_fetcher