PPAPI: Fix destructor ordering problem for main-thread message loop

ppapi/proxy/plugin_globals.cc

Index: ppapi/proxy/plugin_globals.cc
diff --git a/ppapi/proxy/plugin_globals.cc b/ppapi/proxy/plugin_globals.cc
index 1106a75b5616febf09446d485fed84faf442cc18..2913aa23eb0330685e011332f8f128dcab25656d 100644
--- a/ppapi/proxy/plugin_globals.cc
+++ b/ppapi/proxy/plugin_globals.cc
@@ -76,6 +76,13 @@ PluginGlobals::PluginGlobals(ForTest for_test)
 
 PluginGlobals::~PluginGlobals() {
   DCHECK(plugin_globals_ == this || !plugin_globals_);
+  // Release the main-thread message loop. We should have the last reference
+  // count, so this will delete the MessageLoop resource. We do this before
+  // we clear plugin_globals_, because the Resource destructor tries to access
+  // this PluginGlobals.
+  DCHECK(!loop_for_main_thread_ || loop_for_main_thread_->HasOneRef());
+  loop_for_main_thread_ = NULL;
+
   plugin_globals_ = NULL;
 }