[Media Router] Moves mojo-specific code into mojo/ folder

chrome/browser/media/router/test_helper.cc

 // 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.
 
 #include "chrome/browser/media/router/test_helper.h"
 
 namespace media_router {
 
 MockIssuesObserver::MockIssuesObserver(MediaRouter* router)
     : IssuesObserver(router) {}
 MockIssuesObserver::~MockIssuesObserver() {}
 
 MockMediaSinksObserver::MockMediaSinksObserver(MediaRouter* router,
                                                const MediaSource& source,
                                                const GURL& origin)
     : MediaSinksObserver(router, source, origin) {}
 MockMediaSinksObserver::~MockMediaSinksObserver() {
 }
 
 MockMediaRoutesObserver::MockMediaRoutesObserver(MediaRouter* router,
     const MediaSource::Id source_id)
     : MediaRoutesObserver(router, source_id) {
 }
 MockMediaRoutesObserver::~MockMediaRoutesObserver() {
 }
 
-MockEventPageTracker::MockEventPageTracker() {
-}
-MockEventPageTracker::~MockEventPageTracker() {
-}
-
 MockPresentationConnectionStateChangedCallback::
     MockPresentationConnectionStateChangedCallback() = default;
 
 MockPresentationConnectionStateChangedCallback::
     ~MockPresentationConnectionStateChangedCallback() = default;
 
 }  // namespace media_router