Reduce the copying of string data between C++ and javascript in proxy_resolver_v8.cc.

net/proxy/proxy_resolver_v8_unittest.cc

Index: net/proxy/proxy_resolver_v8_unittest.cc
===================================================================
--- net/proxy/proxy_resolver_v8_unittest.cc	(revision 51195)
+++ net/proxy/proxy_resolver_v8_unittest.cc	(working copy)
@@ -109,7 +109,7 @@
     }
 
     // Load the PAC script into the ProxyResolver.
-    return SetPacScriptByData(file_contents, NULL);
+    return SetPacScriptByData(UTF8ToUTF16(file_contents), NULL);
   }
 };
 
@@ -366,7 +366,7 @@
   EXPECT_EQ(OK, result);
 
   // Clear it, by initializing with an empty string.
-  resolver.SetPacScriptByData(std::string(), NULL);
+  resolver.SetPacScriptByData(string16(), NULL);
 
   // Resolve should fail again now.
   result = resolver.GetProxyForURL(kQueryUrl, &proxy_info, NULL, NULL,