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

ppapi/tests/test_graphics_2d.cc

Index: ppapi/tests/test_graphics_2d.cc
diff --git a/ppapi/tests/test_graphics_2d.cc b/ppapi/tests/test_graphics_2d.cc
index ad81f4fe3564c2ab77d94bf696725c7911a8fe5a..1ffb531e391f0bf112d8db618d024d0dd508d163 100644
--- a/ppapi/tests/test_graphics_2d.cc
+++ b/ppapi/tests/test_graphics_2d.cc
@@ -653,7 +653,7 @@ void TestGraphics2D::ResetViewChangedState() {
 }
 
 bool TestGraphics2D::WaitUntilViewChanged() {
-  // Run a nested message loop. It will exit either on ViewChanged or if the
+  // Run a nested run loop. It will exit either on ViewChanged or if the
   // timeout happens.
 
   // If view changed before we have chance to run message loop, return directly.