Make profiling lock global rather than per Target

Source/devtools/front_end/profiler/CanvasProfileView.js

Index: Source/devtools/front_end/profiler/CanvasProfileView.js
diff --git a/Source/devtools/front_end/profiler/CanvasProfileView.js b/Source/devtools/front_end/profiler/CanvasProfileView.js
index 370687ca0961da5edf4d498b556a4a01980e71cc..35733ebac8d045b392ee8424db61e0994e268d60 100644
--- a/Source/devtools/front_end/profiler/CanvasProfileView.js
+++ b/Source/devtools/front_end/profiler/CanvasProfileView.js
@@ -700,22 +700,22 @@ WebInspector.CanvasProfileType.prototype = {
     _runSingleFrameCapturing: function()
     {
         var frameId = this._selectedFrameId();
-        this._target.profilingLock.acquire();
+        WebInspector.profilingLock.acquire();
         CanvasAgent.captureFrame(frameId, this._didStartCapturingFrame.bind(this, frameId));
-        this._target.profilingLock.release();
+        WebInspector.profilingLock.release();
     },
 
     _startFrameCapturing: function()
     {
         var frameId = this._selectedFrameId();
-        this._target.profilingLock.acquire();
+        WebInspector.profilingLock.acquire();
         CanvasAgent.startCapturing(frameId, this._didStartCapturingFrame.bind(this, frameId));
     },
 
     _stopFrameCapturing: function()
     {
         if (!this._lastProfileHeader) {
-            this._target.profilingLock.release();
+            WebInspector.profilingLock.release();
             return;
         }
         var profileHeader = this._lastProfileHeader;
@@ -726,7 +726,7 @@ WebInspector.CanvasProfileType.prototype = {
             profileHeader._updateCapturingStatus();
         }
         CanvasAgent.stopCapturing(traceLogId, didStopCapturing);
-        this._target.profilingLock.release();
+        WebInspector.profilingLock.release();
     },
 
     /**