Remove ComponentLoader's unnecessary string copy.

chrome/browser/extensions/component_loader.h

Index: chrome/browser/extensions/component_loader.h
diff --git a/chrome/browser/extensions/component_loader.h b/chrome/browser/extensions/component_loader.h
index c9d8f6545e63007b3ac23eba25497241c0a172c2..a09441cdf24dacacd2cb64c6f6028f52b97c2e7a 100644
--- a/chrome/browser/extensions/component_loader.h
+++ b/chrome/browser/extensions/component_loader.h
@@ -55,7 +55,7 @@ class ComponentLoader {
   //
   //   ssh-keygen -t rsa -b 1024 -N '' -f /tmp/key.pem
   //   openssl rsa -pubout -outform DER < /tmp/key.pem 2>/dev/null | base64 -w 0
-  std::string Add(const std::string& manifest_contents,
+  std::string Add(const base::StringPiece& manifest_contents,
                   const base::FilePath& root_directory);
 
   // Convenience method for registering a component extension by resource id.
@@ -133,7 +133,7 @@ class ComponentLoader {
   base::DictionaryValue* ParseManifest(
       base::StringPiece manifest_contents) const;
 
-  std::string Add(const std::string& manifest_contents,
+  std::string Add(const base::StringPiece& manifest_contents,
                   const base::FilePath& root_directory,
                   bool skip_whitelist);
   std::string Add(const base::DictionaryValue* parsed_manifest,