[Favicon] Add new fallback icon rendering flow.

components/favicon_base/fallback_icon_service.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 COMPONENTS_FAVICON_BASE_FAVICON_FALLBACK_ICON_SERVICE_H_
+#define COMPONENTS_FAVICON_BASE_FAVICON_FALLBACK_ICON_SERVICE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"

[pkotwicz, 2015/01/23 16:00:48]

Remove the above include because you no longer use it

[huangs, 2015/01/23 19:47:52]

Done.

+#include "base/macros.h"
+
+class GURL;
+
+namespace gfx {
+class Canvas;
+}
+
+namespace favicon_base {
+
+class FallbackIconStyle;
+
+// A service to provide methods to render fallback favicons.
+class FallbackIconService {
+ public:
+  FallbackIconService();
+  ~FallbackIconService();
+
+  // Renders a fallback icon synchronously and returns the bitmap. Returns an
+  // empty std::vector on failure.
+  std::vector<unsigned char> RenderFallbackIconBitmap(
+      const GURL& icon_url,
+      int size_in_pixels,
+      const FallbackIconStyle& style);
+
+ private:
+  // Renders a fallback icon on |canvas| at position (|x|, |y|).
+  void DrawFallbackIcon(const GURL& icon_url,
+                        int x,
+                        int y,
+                        int size_in_pixels,

[pkotwicz, 2015/01/23 16:00:48]

Nit: |size_in_pixels| -> |size|

[huangs, 2015/01/23 19:47:52]

Done, updated comment to reflect this.

Also updated for RenderFallbackIconBitmap() above.

+                        const FallbackIconStyle& style,
+                        gfx::Canvas* canvas);
+
+  std::vector<std::string> fallback_icon_font_list_;;
+
+  DISALLOW_COPY_AND_ASSIGN(FallbackIconService);
+};
+
+}  // namespace favicon_base
+
+#endif  // COMPONENTS_FAVICON_BASE_FAVICON_FALLBACK_ICON_SERVICE_H_