[DevTools] Access cpu profiler only when JS capability is present.

third_party/WebKit/Source/devtools/front_end/profiler/CPUProfileView.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 171 matching lines @@
           scriptId: scriptLocation.scriptId,
           url: script ? script.contentURL() : '',
           lineNumber: scriptLocation.lineNumber,
           columnNumber: scriptLocation.columnNumber || 0
         }]);
 
     target.consoleModel.addMessage(message);
   }
 
   startRecordingProfile() {
-    var target = UI.context.flavor(SDK.Target);
-    if (this.profileBeingRecorded() || !target)
+    var cpuProfilerModel = UI.context.flavor(SDK.CPUProfilerModel);
+    if (this.profileBeingRecorded() || !cpuProfilerModel)
       return;
-    var profile = new Profiler.CPUProfileHeader(target, this);
+    var profile = new Profiler.CPUProfileHeader(cpuProfilerModel.target(), this);
     this.setProfileBeingRecorded(profile);
     SDK.targetManager.suspendAllTargets();
     this.addProfile(profile);
     profile.updateStatus(Common.UIString('Recording\u2026'));
     this._recording = true;
-    target.cpuProfilerModel.startRecording();
+    cpuProfilerModel.startRecording();
   }
 
   stopRecordingProfile() {
     this._recording = false;
     if (!this.profileBeingRecorded() || !this.profileBeingRecorded().target())
       return;
 
     var recordedProfile;
 
     /**
@@ skipping 11 matching lines @@
     }
 
     /**
      * @this {Profiler.CPUProfileType}
      */
     function fireEvent() {
       this.dispatchEventToListeners(Profiler.ProfileType.Events.ProfileComplete, recordedProfile);
     }
 
     this.profileBeingRecorded()
         .target()

[alph, 2017/02/28 23:59:13]

nit: I'd rather write the synchronous part in a single line.

[dgozman, 2017/03/01 00:18:41]

That's what I did, but formatter thinks differently.

-        .cpuProfilerModel.stopRecording()
+        .model(SDK.CPUProfilerModel)
+        .stopRecording()
         .then(didStopProfiling.bind(this))
         .then(SDK.targetManager.resumeAllTargets.bind(SDK.targetManager))
         .then(fireEvent.bind(this));
   }
 
   /**
    * @override
    * @param {string} title
    * @return {!Profiler.ProfileHeader}
    */
@@ skipping 213 matching lines @@
    * @param {!SDK.CPUProfileNode} node
    */
   constructor(depth, duration, startTime, selfTime, node) {
     this.depth = depth;
     this.duration = duration;
     this.startTime = startTime;
     this.selfTime = selfTime;
     this.node = node;
   }
 };