[Icons NTP] Refactor large_icon_source to extract the logic shared between desktop and Android to f…

components/favicon/core/large_icon_service.cc

+// 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.
+
+#include "components/favicon/core/large_icon_service.h"
+
+#include "components/favicon/core/favicon_service.h"
+#include "components/favicon_base/fallback_icon_style.h"
+#include "components/favicon_base/favicon_types.h"
+
+namespace favicon {
+
+LargeIconService::LargeIconService(FaviconService* favicon_service)
+    : favicon_service_(favicon_service) {
+  large_icon_types_.push_back(favicon_base::IconType::FAVICON);
+  large_icon_types_.push_back(favicon_base::IconType::TOUCH_ICON);
+  large_icon_types_.push_back(favicon_base::IconType::TOUCH_PRECOMPOSED_ICON);
+}
+
+LargeIconService::~LargeIconService() {
+}
+
+base::CancelableTaskTracker::TaskId
+    LargeIconService::GetLargeIconOrFallbackStyle(
+        const GURL& page_url,
+        int desired_size_in_pixel,
+        const favicon_base::LargeIconCallback& callback,
+        base::CancelableTaskTracker* tracker) {
+  // TODO(beaudoin): For now this is just a wrapper around
+  //   GetLargestRawFaviconForPageURL. Add the logic required to select the best
+  //   possible large icon. Also add logic to fetch-on-demand when the URL of
+  //   a large icon is known but its bitmap is not available.
+  return favicon_service_->GetLargestRawFaviconForPageURL(
+      page_url,
+      large_icon_types_,
+      desired_size_in_pixel,
+      base::Bind(&LargeIconService::RunLargeIconCallback,
+                 base::Unretained(this), callback, desired_size_in_pixel),
+      tracker);
+}
+
+void LargeIconService::RunLargeIconCallback(
+    const favicon_base::LargeIconCallback& callback,
+    int desired_size_in_pixel,
+    const favicon_base::FaviconRawBitmapResult& bitmap_result) {
+  // If there are no bitmaps, return a result with an empty |bitmap| and a
+  // default |fallback_icon_style|.
+  favicon_base::LargeIconResult result;
+  if (!bitmap_result.is_valid()) {
+    callback.Run(result);
+    return;
+  }
+
+  // If there is a bitmap but it's smaller than the requested size or
+  // non-square, compute its dominant color and use it as background in
+  // |fallback_icon_style|.
+  if (bitmap_result.pixel_size.width() < desired_size_in_pixel ||
+      bitmap_result.pixel_size.height() < desired_size_in_pixel ||
+      bitmap_result.pixel_size.width() != bitmap_result.pixel_size.height()) {
+    // TODO(beaudoin): Resize the icon if it's large enough. Alternatively,
+    // return it and let the HTML resize it.
+    result.fallback_icon_style.reset(new favicon_base::FallbackIconStyle());
+    favicon_base::SetDominantColorAsBackground(
+        bitmap_result.bitmap_data, result.fallback_icon_style.get());
+    callback.Run(result);
+    return;
+  }
+
+  // The bitmap is square and at least as large as the requested one, return
+  // it.
+  // TODO(beaudoin): Resize the icon if it's too large. Alternatively, return
+  // it and let the HTML resize it.
+  result.bitmap = bitmap_result;
+  callback.Run(result);
+}
+
+}  // namespace favicon