Initialize FilePath with FilePath::FilePath(string) instead of FilePath::AppendASCII(string).

FilePath::AppendASCII(string) expects string to be relative path only.
BUG=142421

Review URL: https://chromiumcodereview.appspot.com/10832379

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@152248 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/gpu/gpu_benchmarking_extension.cc

@@ -214,8 +214,8 @@ class GpuBenchmarkingWrapper : public v8::Extension {
     if (!benchmark_support)
       return v8::Undefined();
 
-    FilePath dirpath;
-    dirpath = dirpath.AppendASCII(*dirname);
+    FilePath dirpath(FilePath::StringType(*dirname,
+                                          *dirname + dirname.length()));
     if (!file_util::CreateDirectory(dirpath) ||
         !file_util::PathIsWritable(dirpath)) {
       std::string msg("Path is not writable: ");