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

extensions/renderer/api/serial/serial_api_unittest.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 "device/serial/serial_device_enumerator.h"
 #include "device/serial/serial_service_impl.h"
 #include "device/serial/test_serial_io_handler.h"
 #include "extensions/renderer/api_test_base.h"
 #include "grit/extensions_renderer_resources.h"
 
@@ skipping 295 matching lines @@
 
   virtual void SetUp() OVERRIDE {
     ApiTestBase::SetUp();
     env()->RegisterModule("serial", IDR_SERIAL_CUSTOM_BINDINGS_JS);
     env()->RegisterModule("serial_service", IDR_SERIAL_SERVICE_JS);
     env()->RegisterModule("device/serial/serial.mojom", IDR_SERIAL_MOJOM_JS);
     service_provider()->AddService<device::serial::SerialService>(base::Bind(
         &SerialApiTest::CreateSerialService, base::Unretained(this)));
   }
 
-  virtual void TearDown() OVERRIDE {
-    if (io_handler_.get())
-      EXPECT_TRUE(io_handler_->HasOneRef());
-    ApiTestBase::TearDown();
-  }
-
   scoped_refptr<TestIoHandlerBase> io_handler_;
 
  private:
   scoped_refptr<device::SerialIoHandler> GetIoHandler() {
     if (!io_handler_.get())
       io_handler_ = new TestIoHandlerBase;
     return io_handler_;
   }
 
   void CreateSerialService(
@@ skipping 106 matching lines @@
 
 TEST_F(SerialApiTest, FlushUnknownConnectionId) {
   RunTest("serial_unittest.js", "testFlushUnknownConnectionId");
 }
 
 TEST_F(SerialApiTest, SetPausedUnknownConnectionId) {
   RunTest("serial_unittest.js", "testSetPausedUnknownConnectionId");
 }
 
 }  // namespace extensions