Report PPAPI plugin load error code to UMA.

chrome/browser/load_library_perf_test.cc

Index: chrome/browser/load_library_perf_test.cc
diff --git a/chrome/browser/load_library_perf_test.cc b/chrome/browser/load_library_perf_test.cc
index c35cd0bb86942fffd17b02d2aa49642ef708ec53..d869e54d8761628e0ec9ba582a058d57080a6343 100644
--- a/chrome/browser/load_library_perf_test.cc
+++ b/chrome/browser/load_library_perf_test.cc
@@ -28,12 +28,12 @@ void MeasureSizeAndTimeToLoadNativeLibrary(const base::FilePath& library_name) {
                          "bytes",
                          true);
 
-  std::string error;
+  base::NativeLibraryLoadError error;
   base::TimeTicks start = base::TimeTicks::HighResNow();
   base::NativeLibrary native_library =
       base::LoadNativeLibrary(library_path, &error);
   double delta = (base::TimeTicks::HighResNow() - start).InMillisecondsF();
-  ASSERT_TRUE(native_library) << "Error loading library: " << error;
+  ASSERT_TRUE(native_library) << "Error loading library: " << error.ToString();
   base::UnloadNativeLibrary(native_library);
   perf_test::PrintResult("time_to_load_library",
                          "",