[Icons NTP] Refactor large_icon_source to extract the logic shared between desktop and Android to a new large_icon_service.

This is required since the Android implementation of the icon-based NTP will rely on custom Java code to render the fallback. As a result we want to share the logic needed to retrieve large icons and to compute the fallback style without needing them to go through the full-featured chrome://large-icon that performs the rendering of fallback icons. The Java code will hook directly into the large_icon_service.

This CL also fixes a bug, making sure only non-square icons can be returned as large icons.

Besides this, this CL doesn't change the behavior but will make it possible to add the large icon selection logic to large_icon_service where it can be shared with the Android code.

BUG=467712

Review URL: https://codereview.chromium.org/1092873002

Cr-Commit-Position: refs/heads/master@{#326325}

1 files changed, 6 insertions, 0 deletions

diff --git a/components/favicon_base/favicon_callback.h b/components/favicon_base/favicon_callback.h
index 7616a11..96029f1 100644
--- a/components/favicon_base/favicon_callback.h
+++ b/components/favicon_base/favicon_callback.h
@@ -13,6 +13,7 @@ namespace favicon_base {
 
 struct FaviconRawBitmapResult;
 struct FaviconImageResult;
+struct LargeIconResult;
 
 // Callback for functions that can be used to return a |gfx::Image| and the
 // |GURL| it is loaded from. They are returned as a |FaviconImageResult| object.
@@ -29,6 +30,11 @@ typedef base::Callback<void(const FaviconRawBitmapResult&)>
 typedef base::Callback<void(const std::vector<FaviconRawBitmapResult>&)>
     FaviconResultsCallback;
 
+// Callback for functions returning data for a large icon. |LargeIconResult|
+// will contain either the raw bitmap for a large icon or the style of the
+// fallback to use if a sufficiently large icon could not be found.
+typedef base::Callback<void(const LargeIconResult&)> LargeIconCallback;
+
 }  // namespace favicon_base
 
 #endif  // COMPONENTS_FAVICON_BASE_FAVICON_CALLBACK_H_