Make USB a ContextLifecycleObserver.

third_party/WebKit/Source/modules/webusb/USB.h

 // Copyright 2015 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.
 
 #ifndef USB_h
 #define USB_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/ContextLifecycleObserver.h"
 #include "core/events/EventTarget.h"
-#include "core/frame/LocalFrameLifecycleObserver.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/webusb/WebUSBClient.h"
 
 namespace blink {
 
 class LocalFrame;
 class ScriptState;
 class USBDeviceRequestOptions;
 class WebUSBDevice;
 
 class USB final
     : public RefCountedGarbageCollectedEventTargetWithInlineData<USB>
-    , public LocalFrameLifecycleObserver
+    , public ContextLifecycleObserver
     , public WebUSBClient::Observer {
     DEFINE_WRAPPERTYPEINFO();
     REFCOUNTED_GARBAGE_COLLECTED_EVENT_TARGET(USB);
     USING_GARBAGE_COLLECTED_MIXIN(USB);
 public:
     static USB* create(LocalFrame& frame)

[haraken, 2016/04/06 01:15:42]

Can you make USB::create take Document instead of LocalFrame? Now USB is not
related to LocalFrame.

[Reilly Grant (use Gerrit), 2016/04/06 01:21:56]

I cannot because I need the USBController (or in the future, the
ServiceRegistry) which is attached to the frame.

     {
         return new USB(frame);
     }
 
     ~USB() override;
 
     // USB.idl
     ScriptPromise getDevices(ScriptState*);
     ScriptPromise requestDevice(ScriptState*, const USBDeviceRequestOptions&);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(connect);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(disconnect);
 
     // EventTarget overrides.
     ExecutionContext* getExecutionContext() const override;
     const AtomicString& interfaceName() const override;
 
-    // LocalFrameLifecycleObserver overrides.
-    void willDetachFrameHost() override;
+    // ContextLifecycleObserver overrides.
+    void contextDestroyed() override;
 
     // WebUSBClient::Observer overrides.
     void onDeviceConnected(WebPassOwnPtr<WebUSBDevice>) override;
     void onDeviceDisconnected(WebPassOwnPtr<WebUSBDevice>) override;
 
     DECLARE_VIRTUAL_TRACE();
     EAGERLY_FINALIZE();
 
 private:
     explicit USB(LocalFrame& frame);
 
     WebUSBClient* m_client;
 };
 
 } // namespace blink
 
 #endif // USB_h