Make some updates to extension iconography.

chrome/browser/ui/webui/extensions/extension_icon_source.h

Index: chrome/browser/ui/webui/extensions/extension_icon_source.h
diff --git a/chrome/browser/ui/webui/extensions/extension_icon_source.h b/chrome/browser/ui/webui/extensions/extension_icon_source.h
index 47ebee121996171791f5d58d93c25e110b381df3..586ca2b326e0a0b52df4c5275cc7e8c406c076f0 100644
--- a/chrome/browser/ui/webui/extensions/extension_icon_source.h
+++ b/chrome/browser/ui/webui/extensions/extension_icon_source.h
@@ -56,14 +56,11 @@ class ExtensionIconSource : public content::URLDataSource,
 
   // Gets the URL of the |extension| icon in the given |icon_size|, falling back
   // based on the |match| type. If |grayscale|, the URL will be for the
-  // desaturated version of the icon. |exists|, if non-NULL, will be set to true
-  // if the icon exists; false if it will lead to a default or not-present
-  // image.
+  // desaturated version of the icon.
   static GURL GetIconURL(const Extension* extension,
                          int icon_size,
                          ExtensionIconSet::MatchType match,
-                         bool grayscale,
-                         bool* exists);
+                         bool grayscale);
 
   // A public utility function for accessing the bitmap of the image specified
   // by |resource_id|.