Have PlatformEventObserver implementations orderly stop on destruction.

content/shell/renderer/test_runner/gamepad_controller.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 "content/shell/renderer/test_runner/gamepad_controller.h"
 
 #include "content/shell/renderer/test_runner/web_test_delegate.h"
 #include "gin/arguments.h"
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
@@ skipping 133 matching lines @@
   delegate->SetGamepadProvider(scoped_ptr<RendererGamepadProvider>(controller));
   return controller->weak_factory_.GetWeakPtr();
 }
 
 GamepadController::GamepadController()
     : RendererGamepadProvider(0),
       weak_factory_(this) {
   Reset();
 }
 
-GamepadController::~GamepadController() {}
+GamepadController::~GamepadController() {
+  StopIfObserving();
+}
 
 void GamepadController::Reset() {
   memset(&gamepads_, 0, sizeof(gamepads_));
 }
 
 void GamepadController::Install(WebFrame* frame) {
   GamepadControllerBindings::Install(weak_factory_.GetWeakPtr(), frame);
 }
 
 
@@ skipping 81 matching lines @@
 
 void GamepadController::SetAxisData(int index, int axis, double data) {
   if (index < 0 || index >= static_cast<int>(WebGamepads::itemsLengthCap))
     return;
   if (axis < 0 || axis >= static_cast<int>(WebGamepad::axesLengthCap))
     return;
   gamepads_.items[index].axes[axis] = data;
 }
 
 }  // namespace content