DevTools: make paint profiler target-aware

Source/devtools/front_end/timeline/TimelineLayersView.js

Index: Source/devtools/front_end/timeline/TimelineLayersView.js
diff --git a/Source/devtools/front_end/timeline/TimelineLayersView.js b/Source/devtools/front_end/timeline/TimelineLayersView.js
index e1080000f6a0be62833b223abcd82558494e5f86..6b61e57050a165af3f1c230a43f850fffb0b74a1 100644
--- a/Source/devtools/front_end/timeline/TimelineLayersView.js
+++ b/Source/devtools/front_end/timeline/TimelineLayersView.js
@@ -27,37 +27,32 @@ WebInspector.TimelineLayersView.prototype = {
     showLayerTree: function(deferredLayerTree, paints)
     {
         this._disposeTiles();
-        if (!this.isShowing()) {
-            this._pendingLayerTree = deferredLayerTree,
-            this._pendingPaints = paints;
-            return;
-        }
-        this._actuallyShowLayerTree(deferredLayerTree, paints);
+        this._deferredLayerTree = deferredLayerTree;
+        this._paints = paints;
+        if (this.isShowing())
+            this._update();
+        else
+            this._updateWhenVisible = true;
     },
 
     wasShown: function()
     {
-        if (!this._pendingLayerTree)
-            return;
-        this._actuallyShowLayerTree(this._pendingLayerTree, this._pendingPaints);
-        this._pendingLayerTree = null;
-        this._pendingPaints = null;
+        if (this._updateWhenVisible) {
+            this._updateWhenVisible = false;
+            this._update();
+        }
     },
 
-    /**
-     * @param {!WebInspector.DeferredLayerTree} deferredLayerTree
-     * @param {?Array.<!WebInspector.LayerPaintEvent>} paints
-     */
-    _actuallyShowLayerTree: function(deferredLayerTree, paints)
+    _update: function()
     {
         var layerTree;
 
-        this._target = deferredLayerTree.target();
+        this._target = this._deferredLayerTree.target();
         var originalTiles = this._paintTiles;
         var tilesReadyBarrier = new CallbackBarrier();
-        deferredLayerTree.resolve(tilesReadyBarrier.createCallback(onLayersReady));
-        for (var i = 0; paints && i < paints.length; ++i)
-            WebInspector.PaintProfilerSnapshot.load(paints[i].picture, tilesReadyBarrier.createCallback(onSnapshotLoaded.bind(this, paints[i])));
+        this._deferredLayerTree.resolve(tilesReadyBarrier.createCallback(onLayersReady));
+        for (var i = 0; this._paints && i < this._paints.length; ++i)
+            WebInspector.PaintProfilerSnapshot.load(this._target, this._paints[i].picture, tilesReadyBarrier.createCallback(onSnapshotLoaded.bind(this, this._paints[i])));
         tilesReadyBarrier.callWhenDone(onLayersAndTilesReady.bind(this));
 
         /**