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

extensions/renderer/module_system_test.cc

Index: extensions/renderer/module_system_test.cc
diff --git a/extensions/renderer/module_system_test.cc b/extensions/renderer/module_system_test.cc
index 4f4675e625610be86972476ac2dca54fd4e68d07..f2ce8ac1b96b9cf71151d2928d5fe48f5bcfc283 100644
--- a/extensions/renderer/module_system_test.cc
+++ b/extensions/renderer/module_system_test.cc
@@ -221,6 +221,9 @@ void ModuleSystemTest::TearDown() {
   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() {