Bug 1619221 - Remove can-debug-sw-updated event r=ladybenko,daisuke,devtools-backward-compat-reviewers

Depends on D81343

All the client side consumers for the event have been removed.
Since we don't support forward compatibility, we can simply remove the event.

Differential Revision: https://phabricator.services.mozilla.com/D81344

devtools/server/actors/device.js

@@ -9,10 +9,8 @@ const Services = require("Services");
 const protocol = require("devtools/shared/protocol");
 const { LongStringActor } = require("devtools/server/actors/string");
 const {
-  addDebugServiceWorkersListener,
   canDebugServiceWorkers,
   isParentInterceptEnabled,
-  removeDebugServiceWorkersListener,
 } = require("devtools/shared/service-workers-debug-helper");
 
 const { DevToolsServer } = require("devtools/server/devtools-server");
@@ -30,11 +28,6 @@ exports.DeviceActor = protocol.ActorClassWithSpec(deviceSpec, {
       this._window.addEventListener("pageshow", this._onPageShow, true);
     }
     this._acquireWakeLock();
-
-    this._onDebugServiceWorkersUpdated = this._onDebugServiceWorkersUpdated.bind(
-      this
-    );
-    addDebugServiceWorkersListener(this._onDebugServiceWorkersUpdated);
   },
 
   destroy: function() {
@@ -43,11 +36,6 @@ exports.DeviceActor = protocol.ActorClassWithSpec(deviceSpec, {
     if (this._window) {
       this._window.removeEventListener("pageshow", this._onPageShow, true);
     }
-    removeDebugServiceWorkersListener(this._onDebugServiceWorkersUpdated);
-  },
-
-  _onDebugServiceWorkersUpdated: function() {
-    this.emit("can-debug-sw-updated", canDebugServiceWorkers());
   },
 
   getDescription: function() {

devtools/shared/service-workers-debug-helper.js

@@ -19,36 +19,8 @@ XPCOMUtils.defineLazyServiceGetter(
  * This depends both on the current multiprocess (e10s) configuration and on the
  * usage of the new service worker implementation
  * (dom.serviceWorkers.parent_intercept = true).
- *
- * Since this can be changed on the fly, there are subscribe/unsubscribe functions
- * to get notified of this.
  */
 
-const PROCESS_COUNT_PREF = "dom.ipc.processCount";
-const MULTI_OPTOUT_PREF = "dom.ipc.multiOptOut";
-
-function addDebugServiceWorkersListener(listener) {
-  // Some notes about these observers:
-  // - nsIPrefBranch.addObserver observes prefixes. In reality, watching
-  //   PROCESS_COUNT_PREF watches two separate prefs:
-  //   dom.ipc.processCount *and* dom.ipc.processCount.web. Because these
-  //   are the two ways that we control the number of content processes,
-  //   that works perfectly fine.
-  // - The user might opt in or out of multi by setting the multi opt out
-  //   pref. That affects whether we need to show our warning, so we need to
-  //   update our state when that pref changes.
-  // - In all cases, we don't have to manually check which pref changed to
-  //   what. The platform code in nsIXULRuntime.maxWebProcessCount does all
-  //   of that for us.
-  Services.prefs.addObserver(PROCESS_COUNT_PREF, listener);
-  Services.prefs.addObserver(MULTI_OPTOUT_PREF, listener);
-}
-
-function removeDebugServiceWorkersListener(listener) {
-  Services.prefs.removeObserver(PROCESS_COUNT_PREF, listener);
-  Services.prefs.removeObserver(MULTI_OPTOUT_PREF, listener);
-}
-
 function canDebugServiceWorkers() {
   const isE10s = Services.appinfo.browserTabsRemoteAutostart;
   const processCount = Services.appinfo.maxWebProcessCount;
@@ -65,8 +37,6 @@ function isParentInterceptEnabled() {
 }
 
 module.exports = {
-  addDebugServiceWorkersListener,
   canDebugServiceWorkers,
   isParentInterceptEnabled,
-  removeDebugServiceWorkersListener,
 };

devtools/shared/specs/device.js

@@ -3,17 +3,10 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 
-const { Arg, RetVal, generateActorSpec } = require("devtools/shared/protocol");
+const { RetVal, generateActorSpec } = require("devtools/shared/protocol");
 const deviceSpec = generateActorSpec({
   typeName: "device",
 
-  events: {
-    "can-debug-sw-updated": {
-      type: "can-debug-sw-updated",
-      canDebugServiceWorkers: Arg(0, "boolean"),
-    },
-  },
-
   methods: {
     getDescription: { request: {}, response: { value: RetVal("json") } },
     screenshotToDataURL: {