PPAPI: Release renderer Var refcount when returning to plugin

ppapi/proxy/serialized_var_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/proxy/ppapi_proxy_test.h"
 
+#include "ppapi/proxy/proxy_object_var.h"
 #include "ppapi/proxy/serialized_var.h"
 #include "ppapi/shared_impl/proxy_lock.h"
 
 namespace ppapi {
 namespace proxy {
 
 namespace {
 
 PP_Var MakeObjectVar(int64_t object_id) {
   PP_Var ret;
@@ skipping 248 matching lines @@
     EXPECT_EQ(old_message_count, sink().message_count());
   }
 
   // Since we didn't keep any refs to the objects or strings, so they should
   // have been freed.
   EXPECT_EQ(-1, var_tracker().GetRefCountForObject(plugin_objects[0]));
   EXPECT_EQ(-1, var_tracker().GetRefCountForObject(plugin_objects[1]));
   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));
+  }
+
+  {
+    // Note this is as little weird; we're testing the behavior of the host-
+    // side of the proxy, but we use ProxyObjectVar, because this unit test
+    // doesn't have access to stuff in content/renderer/pepper. The ref-counting
+    // behavior should be the same, however. All we're really testing
+    // is the code in ppapi/proxy (HostVarSerializationRules).
+    scoped_refptr<Var> obj_var = new ProxyObjectVar(NULL, 1234);
+    PP_Var obj_pp_var = obj_var->GetPPVar();
+    EXPECT_EQ(1, var_tracker().GetRefCountForObject(obj_pp_var));
+    GetDispatcher()->serialization_rules()->BeginSendPassRef(obj_pp_var);
+    GetDispatcher()->serialization_rules()->EndSendPassRef(obj_pp_var);
+    // The host side for object vars always keeps 1 ref on behalf of the plugin.
+    // See HostVarSerializationRules and PluginVarSerializationRules for an
+    // explanation.
+    EXPECT_EQ(1, var_tracker().GetRefCountForObject(obj_pp_var));
+    var_tracker().ReleaseVar(obj_pp_var);
+  }
+}
+
 // Tests the plugin receiving a var as a return value from the browser
 // two different times (passing ownership).
 TEST_F(SerializedVarTest, PluginReceiveReturn) {
   ProxyAutoLock lock;
   PP_Var host_object = MakeObjectVar(0x31337);
 
   PP_Var plugin_object;
   {
     // Receive the first param, we should be tracking it with a refcount of 1.
     SerializedVarTestConstructor input1(host_object);
@@ skipping 60 matching lines @@
   }
 
   // When the ReturnValue object goes out of scope, it should have sent a
   // release message to the browser.
   EXPECT_EQ(-1, var_tracker().GetRefCountForObject(plugin_object));
   EXPECT_EQ(1u, sink().message_count());
 }
 
 }  // namespace proxy
 }  // namespace ppapi