Clean up the IconLoader.

chrome/browser/icon_loader_mac.mm

Index: chrome/browser/icon_loader_mac.mm
diff --git a/chrome/browser/icon_loader_mac.mm b/chrome/browser/icon_loader_mac.mm
index 6abeb4734b6aa759fa01aacdce6229f8e56054ec..3a31a1d7089e06b0a1bf42dc8be1354765f6cee6 100644
--- a/chrome/browser/icon_loader_mac.mm
+++ b/chrome/browser/icon_loader_mac.mm
@@ -15,17 +15,12 @@
 #include "ui/gfx/image/image_skia_util_mac.h"
 
 // static
-IconGroupID IconLoader::ReadGroupIDFromFilepath(
+IconLoader::IconGroup IconLoader::GroupForFilepath(
     const base::FilePath& filepath) {
   return filepath.Extension();
 }
 
 // static
-bool IconLoader::IsIconMutableFromFilepath(const base::FilePath&) {
-  return false;
-}
-
-// static
 content::BrowserThread::ID IconLoader::ReadIconThreadID() {
   return content::BrowserThread::FILE;
 }