Replace "nested message loop" with "nested run loop" in comments.

ppapi/tests/test_case.h

Index: ppapi/tests/test_case.h
diff --git a/ppapi/tests/test_case.h b/ppapi/tests/test_case.h
index a19895342e64070baa32a8206f35b31d00b6b7e5..9c32309b3e7f2e188f30f6a7cee7fd1f8f2581c1 100644
--- a/ppapi/tests/test_case.h
+++ b/ppapi/tests/test_case.h
@@ -197,7 +197,7 @@ class TestCase {
       // Now give the loop a chance to clean up.
       loop_.PostQuit(true /* should_destroy */);
       loop_.Run();
-      // Tell the main thread to quit its nested message loop, now that the test
+      // Tell the main thread to quit its nested run loop, now that the test
       // is complete.
       TestCase::QuitMainMessageLoop(instance_);
     }