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..8852686e6acca566b429cbc0ae9f602dd8b8690a 100644
--- a/extensions/renderer/module_system_test.cc
+++ b/extensions/renderer/module_system_test.cc
@@ -221,6 +221,18 @@ void ModuleSystemTest::TearDown() {
   EXPECT_EQ(should_assertions_be_made_,
             env_->assert_natives()->assertion_made());
   EXPECT_FALSE(env_->assert_natives()->failed());
+  env_.reset();
+  v8::HeapStatistics stats;
+  isolate_->GetHeapStatistics(&stats);
+  size_t old_heap_size = 0;
+  // Run the GC until the heap size reaches a steady state to ensure that
+  // all the garbage is collected.
+  while (stats.used_heap_size() != old_heap_size) {
+    old_heap_size = stats.used_heap_size();
+    isolate_->RequestGarbageCollectionForTesting(
+        v8::Isolate::kFullGarbageCollection);
+    isolate_->GetHeapStatistics(&stats);
+  }

[not at google - send to devlin, 2014/08/28 15:42:04]

Yikes :(

 }
 
 scoped_ptr<ModuleSystemTestEnvironment> ModuleSystemTest::CreateEnvironment() {