Remove extension process side of chrome.devtools API, it's obsolete.

chrome/test/data/extensions/devtools/timeline_api/background.js

-// Copyright (c) 2012 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.
-
-var receivedEvents = [];
-var devtoolsTabEvents = undefined;
-
-function pageEventListener() {
-  receivedEvents.push("onPageEvent");
-}
-
-function tabCloseListener() {
-  receivedEvents.push("onTabClose");
-}
-
-function setListenersOnTab(tabId) {
-  try {
-    devtoolsTabEvents = chrome.devtools.getTabEvents(tabId);
-    devtoolsTabEvents.onPageEvent.addListener(pageEventListener);
-    devtoolsTabEvents.onTabClose.addListener(tabCloseListener);
-    window.domAutomationController.send(true);
-  } catch(e) {
-    window.domAutomationController.send(false);
-  }
-}
-
-/**
- * Sends true if next event was a onPageEvent and pop it from |receivedEvents|.
- */
-function testReceivePageEvent() {
-  var sawPage = false;
-  if (receivedEvents.length >= 1) {
-    var eventName = receivedEvents.pop();
-    if (eventName === "onPageEvent")
-      sawPage = true;
-    else
-      console.warn('received ' + eventName + '; expecting onPageEvent');
-  }
-  window.domAutomationController.send(sawPage);
-}
-
-/**
- * Sends true if any event is onTabClose and clear |receivedEvents|.
- */
-function testReceiveTabCloseEvent() {
-  var sawTabClose = false;
-  for(var i = 0; i < receivedEvents.length; i++) {
-    if (receivedEvents[i] === 'onTabClose') {
-      sawTabClose = true;
-      break;
-    }
-  }
-  receivedEvents = [];
-  window.domAutomationController.send(sawTabClose);
-}
-
-function unregisterListeners() {
-  devtoolsTabEvents.onPageEvent.removeListener(pageEventListener);
-  devtoolsTabEvents.onTabClose.removeListener(tabCloseListener);
-  window.domAutomationController.send(true);
-}