Generalize ExtensionIconSet to store icon paths for custom size sets

chrome/browser/background/background_application_list_model.cc

Index: chrome/browser/background/background_application_list_model.cc
diff --git a/chrome/browser/background/background_application_list_model.cc b/chrome/browser/background/background_application_list_model.cc
index 3cbb1145b8b55eee13e0553bb6d166b76619cee0..262916e551f6c7ed3d9a97537bee80e669b5cd32 100644
--- a/chrome/browser/background/background_application_list_model.cc
+++ b/chrome/browser/background/background_application_list_model.cc
@@ -73,7 +73,7 @@ class BackgroundApplicationListModel::Application
 
   // Uses the FILE thread to request this extension's icon, sized
   // appropriately.
-  void RequestIcon(ExtensionIconSet::Icons size);
+  void RequestIcon(ExtensionIconSet::ExtensionIcons size);
 
   const Extension* extension_;
   scoped_ptr<gfx::ImageSkia> icon_;
@@ -155,7 +155,7 @@ void BackgroundApplicationListModel::Application::OnImageLoaded(
 }
 
 void BackgroundApplicationListModel::Application::RequestIcon(
-    ExtensionIconSet::Icons size) {
+    ExtensionIconSet::ExtensionIcons size) {
   ExtensionResource resource = extension_->GetIconResource(
       size, ExtensionIconSet::MATCH_BIGGER);
   tracker_.LoadImage(extension_, resource, gfx::Size(size, size),