PPAPI: Release renderer Var refcount when returning to plugin

ppapi/proxy/serialized_var_unittest.cc

Index: ppapi/proxy/serialized_var_unittest.cc
diff --git a/ppapi/proxy/serialized_var_unittest.cc b/ppapi/proxy/serialized_var_unittest.cc
index fcde77795a37b71cf2fa5baa718b040779c420dc..94961afeb04c914c6f28718ac3bcb810bd8ac6c4 100644
--- a/ppapi/proxy/serialized_var_unittest.cc
+++ b/ppapi/proxy/serialized_var_unittest.cc
@@ -272,6 +272,18 @@ TEST_F(SerializedVarTest, PluginVectorReceiveInput) {
   EXPECT_EQ(-1, var_tracker().GetRefCountForObject(plugin_objects2[1]));
 }
 
+// Tests the browser sending a String var as a return value to make sure we
+// ref-count the host side properly.
+typedef HostProxyTest HostSerializedVarTest;
+TEST_F(HostSerializedVarTest, PluginReceiveStringReturn) {
+  PP_Var string_var = StringVar::StringToPPVar("Hello");
+  EXPECT_EQ(1, var_tracker().GetRefCountForObject(string_var));
+  GetDispatcher()->serialization_rules()->BeginSendPassRef(string_var);
+  GetDispatcher()->serialization_rules()->EndSendPassRef(string_var);
+  // It should be gone, so we should get -1 to indicate that.
+  EXPECT_EQ(-1, var_tracker().GetRefCountForObject(string_var));

[raymes, 2015/01/27 00:12:44]

Should we test the object var case too? Or does that get tested somewhere else?

+}
+
 // Tests the plugin receiving a var as a return value from the browser
 // two different times (passing ownership).
 TEST_F(SerializedVarTest, PluginReceiveReturn) {