Make image_decoder a Leaky LazyInstance

chrome/browser/bitmap_fetcher/bitmap_batch_fetcher.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 CHROME_BROWSER_BITMAP_FETCHER_BITMAP_BATCH_FETCHER_H_
+#define CHROME_BROWSER_BITMAP_FETCHER_BITMAP_BATCH_FETCHER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/bitmap_fetcher/bitmap_fetcher_delegate.h"
+#include "chrome/browser/image_batch_decoder.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "url/gurl.h"
+
+namespace net {
+class URLFetcher;
+class URLRequestContextGetter;
+}  // namespace net
+
+namespace chrome {
+
+// Asynchrounously fetches images from the URLs provided in calls to ::Start
+// and returns the decoded Bitmaps to the provided BitmapFetcherDelegate.
+class BitmapBatchFetcher : public net::URLFetcherDelegate {
+ public:
+  BitmapBatchFetcher();
+
+  ~BitmapBatchFetcher() override;
+
+  // Start fetching the URL. The delegate is notified asynchronously when done.
+  // Arguments are used to configure the internal fetcher.
+  // Values for |load_flags| are defined in net/base/load_flags.h.  In general,
+  // |net::LOAD_NORMAL| is appropriate.
+  void Start(net::URLRequestContextGetter* request_context,
+             const std::string& referrer,
+             net::URLRequest::ReferrerPolicy referrer_policy,
+             int load_flags,
+             const GURL& url,
+             BitmapFetcherDelegate* delegate);
+
+  // Methods inherited from URLFetcherDelegate
+
+  // This will be called when the URL has been fetched, successfully or not.
+  // Use accessor methods on |source| to get the results.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+  // This will be called when some part of the response is read. |current|
+  // denotes the number of bytes received up to the call, and |total| is the
+  // expected total size of the response (or -1 if not determined).
+  void OnURLFetchDownloadProgress(const net::URLFetcher* source,
+                                  int64 current,
+                                  int64 total) override;
+
+ private:
+  scoped_refptr<ImageBatchDecoder> image_batch_decoder_;
+  std::map<const net::URLFetcher*, std::pair<GURL, BitmapFetcherDelegate*>>
+    url_fetcher_map_;
+
+  class Delegate : public ImageBatchDecoder::Delegate {
+   public:
+    Delegate(const GURL& url, BitmapFetcherDelegate* delegate)
+       : url_(url), delegate_(delegate) {}
+
+    // Methods inherited from ImageBatchDecoder::Delegate
+
+    // Called when image is decoded. |decoder| is used to identify the image in
+    // case of decoding several images simultaneously.  This will not be called
+    // on the UI thread.
+    void OnImageDecoded(const ImageBatchDecoder* decoder,
+                        const SkBitmap& decoded_image) override;
+
+    // Called when decoding image failed.
+    void OnDecodeImageFailed(const ImageBatchDecoder* decoder) override;
+
+   private:
+    const GURL url_;
+    BitmapFetcherDelegate* delegate_;
+  };
+
+  DISALLOW_COPY_AND_ASSIGN(BitmapBatchFetcher);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_BITMAP_FETCHER_BITMAP_BATCH_FETCHER_H_