Add icon fetching sources

chromium_src/chrome/browser/icon_loader.h

@@ -0,0 +1,105 @@
+// 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_ICON_LOADER_H_
+#define CHROME_BROWSER_ICON_LOADER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
+#include "build/build_config.h"
+#include "content/public/browser/browser_thread.h"
+#include "ui/gfx/image/image.h"
+
+#if defined(OS_WIN)
+// On Windows, we group files by their extension, with several exceptions:
+// .dll, .exe, .ico. See IconManager.h for explanation.
+typedef std::wstring IconGroupID;
+#elif defined(OS_POSIX)
+// On POSIX, we group files by MIME type.
+typedef std::string IconGroupID;
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// A facility to read a file containing an icon asynchronously in the IO
+// thread. Returns the icon in the form of an ImageSkia.
+//
+////////////////////////////////////////////////////////////////////////////////
+class IconLoader : public base::RefCountedThreadSafe<IconLoader> {
+ public:
+  enum IconSize {
+    SMALL = 0,  // 16x16
+    NORMAL,     // 32x32
+    LARGE,      // Windows: 32x32, Linux: 48x48, Mac: Unsupported
+    ALL,        // All sizes available
+  };
+
+  class Delegate {
+   public:
+    // Invoked when an icon group has been read, but before the icon data
+    // is read. If the icon is already cached, this method should call and
+    // return the results of OnImageLoaded with the cached image.
+    virtual bool OnGroupLoaded(IconLoader* source,
+                               const IconGroupID& group) = 0;
+    // Invoked when an icon has been read. |source| is the IconLoader. If the
+    // icon has been successfully loaded, result is non-null. This method must
+    // return true if it is taking ownership of the returned image.
+    virtual bool OnImageLoaded(IconLoader* source,
+                               gfx::Image* result,
+                               const IconGroupID& group) = 0;
+
+   protected:
+    virtual ~Delegate() {}
+  };
+
+  IconLoader(const base::FilePath& file_path,
+             IconSize size,
+             Delegate* delegate);
+
+  // Start reading the icon on the file thread.
+  void Start();
+
+ private:
+  friend class base::RefCountedThreadSafe<IconLoader>;
+
+  virtual ~IconLoader();
+
+  // Get the identifying string for the given file. The implementation
+  // is in icon_loader_[platform].cc.
+  static IconGroupID ReadGroupIDFromFilepath(const base::FilePath& path);
+
+  // Some icons (exe's on windows) can change as they're loaded.
+  static bool IsIconMutableFromFilepath(const base::FilePath& path);
+
+  // The thread ReadIcon() should be called on.
+  static content::BrowserThread::ID ReadIconThreadID();
+
+  void ReadGroup();
+  void OnReadGroup();
+  void ReadIcon();
+
+  void NotifyDelegate();
+
+  // The task runner object of the thread in which we notify the delegate.
+  scoped_refptr<base::SingleThreadTaskRunner> target_task_runner_;
+
+  base::FilePath file_path_;
+
+  IconGroupID group_;
+
+  IconSize icon_size_;
+
+  std::unique_ptr<gfx::Image> image_;
+
+  Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(IconLoader);
+};
+
+#endif  // CHROME_BROWSER_ICON_LOADER_H_