DevTools: do not add paint profiler tab more than once on Layers panel

third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js

Index: third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js b/third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js
index 0986e54bcdd13bd706f249a5dc34920f6f479255..0f9c172f58ee7eed614eabb7382ff1c164aff1f6 100644
--- a/third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js
+++ b/third_party/WebKit/Source/devtools/front_end/layers/LayersPanel.js
@@ -156,9 +156,11 @@ Layers.LayersPanel = class extends UI.PanelWithSidebar {
       if (!snapshotWithRect)
         return;
       this._layerBeingProfiled = selection.layer();
-      this._tabbedPane.appendTab(
-          Layers.LayersPanel.DetailsViewTabs.Profiler, Common.UIString('Profiler'), this._paintProfilerView, undefined,
-          true, true);
+      if (!this._tabbedPane.hasTab(Layers.LayersPanel.DetailsViewTabs.Profiler)) {
+        this._tabbedPane.appendTab(
+            Layers.LayersPanel.DetailsViewTabs.Profiler, Common.UIString('Profiler'), this._paintProfilerView,
+            undefined, true, true);
+      }
       this._tabbedPane.selectTab(Layers.LayersPanel.DetailsViewTabs.Profiler);
       this._paintProfilerView.profile(snapshotWithRect.snapshot);
     });