Break out manifest icon logic from ShortcutHelper

chrome/browser/android/manifest_icon_selector.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_ANDROID_MANIFEST_ICON_SELECTOR_H_
+#define CHROME_BROWSER_ANDROID_MANIFEST_ICON_SELECTOR_H_
+
+#include "base/basictypes.h"
+#include "content/public/common/manifest.h"
+#include "url/gurl.h"
+
+namespace content {
+class WebContents;
+}  // namespace content
+
+namespace IPC {
+class Message;
+}  // namespace IPC
+
+// Selects the icon most closely matching the size constraints.  This follows
+// very basic heuristics -- improvements are welcome.
+class ManifestIconSelector {
+ public:
+  // Runs the algorithm to find the best matching icon in the icons listed in
+  // the Manifest.
+  // Returns the icon url if a suitable icon is found. An empty URL otherwise.
+  static GURL FindBestMatchingIcon(
+      const std::vector<content::Manifest::Icon>& icons,
+      float preferred_size_in_dp,
+      content::WebContents* web_contents);

[mlamouri (slow - plz ping), 2015/01/30 22:32:13]

Wouldn't that be better to not depend on WebContents*? As suggested before, this
method could take the required arguments instead of computing them. I guess
device_scale_factor would be needed in addition of the size in dp or px, I'm not
sure which one would be better to understand for callers. Maybe px?

[gone, 2015/01/30 22:43:30]

The logic is used in three different places, though: once in ShortcutHelper,
once in the new app banners, and once in the unit tests.  I'm not sure if it
makes sense to triplicate the same logic, especially if it's for a image that
will eventually be displayed in Android's UI in dp.

+
+ private:
+  ManifestIconSelector() {}
+  virtual ~ManifestIconSelector() {}
+
+  // Returns an array containing the items in |icons| without the unsupported
+  // image MIME types.
+  static std::vector<content::Manifest::Icon> FilterIconsByType(
+      const std::vector<content::Manifest::Icon>& icons);
+
+  // Runs an algorithm only based on icon declared sizes. It will try to find
+  // size that is the closest to preferred_icon_size_in_px_ but bigger than
+  // preferred_icon_size_in_px_ if possible.
+  // Returns the icon url if a suitable icon is found. An empty URL otherwise.
+  static GURL FindBestMatchingIcon(
+      const std::vector<content::Manifest::Icon>& icons,
+      float density,
+      int preferred_icon_size_in_px);
+
+  // Returns whether the |preferred_icon_size_in_px| is in the given |sizes|.
+  static bool IconSizesContainsPreferredSize(
+      const std::vector<gfx::Size>& sizes,
+      int preferred_icon_size_in_px);
+
+  // Returns whether the 'any' (ie. gfx::Size(0,0)) is in the given |sizes|.
+  static bool IconSizesContainsAny(const std::vector<gfx::Size>& sizes);
+
+  friend class ManifestIconSelectorTest;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestIconSelector);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_MANIFEST_ICON_SELECTOR_H_