PPAPI: Make blocking completion callbacks work.

ppapi/tests/test_case.cc

Index: ppapi/tests/test_case.cc
diff --git a/ppapi/tests/test_case.cc b/ppapi/tests/test_case.cc
index 26f6d40ba5235ec7829e3129b03e913b8d97c404..cc0ba486521c7fc9034bbe81ab792af3b8db9285 100644
--- a/ppapi/tests/test_case.cc
+++ b/ppapi/tests/test_case.cc
@@ -107,8 +107,10 @@ bool TestCase::MatchesFilter(const std::string& test_name,
   return filter.empty() || (test_name == filter);
 }
 
-std::string TestCase::CheckResourcesAndVars() {
-  std::string errors;
+std::string TestCase::CheckResourcesAndVars(std::string errors) {
+  if (!errors.empty())
+    return errors;
+
   if (testing_interface_) {
     // TODO(dmichael): Fix tests that leak resources and enable the following:
     /*
@@ -143,4 +145,17 @@ std::string TestCase::CheckResourcesAndVars() {
   return errors;
 }
 
+// static
+void TestCase::QuitMainMessageLoop(PP_Instance instance) {
+  PP_Instance* heap_instance = new PP_Instance(instance);
+  pp::CompletionCallback callback(&DoQuitMainMessageLoop, heap_instance);
+  pp::Module::Get()->core()->CallOnMainThread(0, callback);
+}
+
+// static
+void TestCase::DoQuitMainMessageLoop(void* pp_instance, int32_t result) {
+  PP_Instance* instance = static_cast<PP_Instance*>(pp_instance);
+  GetTestingInterface()->QuitMessageLoop(*instance);
+  delete instance;
+}