Fix some leaks and failures under valgrind in JS extensions unit tests.

extensions/renderer/module_system_test.cc

 // Copyright 2014 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 "extensions/renderer/module_system_test.h"
 
 #include <map>
 #include <string>
 
 #include "base/callback.h"
@@ skipping 203 matching lines @@
 }
 
 ModuleSystemTest::~ModuleSystemTest() {
 }
 
 void ModuleSystemTest::TearDown() {
   // All tests must assert at least once unless otherwise specified.
   EXPECT_EQ(should_assertions_be_made_,
             env_->assert_natives()->assertion_made());
   EXPECT_FALSE(env_->assert_natives()->failed());
+  env_.reset();

[not at google - send to devlin, 2014/08/27 19:28:58]

env_ is created in the constructor, why do you need to destroy it here?

[Sam McNally, 2014/08/28 07:06:51]

We need to remove the references from either ModuleSystem or ModuleRegistry to
any modules that use gin to wrap a C++ object before running the GC. It appears
that v8 doesn't run finalizers during isolate destruction, so we have to remove
all references and run the GC before the isolate is destroyed.

+  isolate_->RequestGarbageCollectionForTesting(
+      v8::Isolate::kFullGarbageCollection);
 }
 
 scoped_ptr<ModuleSystemTestEnvironment> ModuleSystemTest::CreateEnvironment() {
   return make_scoped_ptr(new ModuleSystemTestEnvironment(isolate_));
 }
 
 void ModuleSystemTest::ExpectNoAssertionsMade() {
   should_assertions_be_made_ = false;
 }
 
 void ModuleSystemTest::RunResolvedPromises() {
   isolate_->RunMicrotasks();
 }
 
 }  // namespace extensions