DevTools: Add energy value under Timeline pie chart

Source/devtools/front_end/TimelinePanel.js

Index: Source/devtools/front_end/TimelinePanel.js
diff --git a/Source/devtools/front_end/TimelinePanel.js b/Source/devtools/front_end/TimelinePanel.js
index 69e664aa5c0acb8feb9f3f6bc2e22f5b0aecf3ff..5a92bc0ddd92914d23092b80fff66ec52b5b7cca 100644
--- a/Source/devtools/front_end/TimelinePanel.js
+++ b/Source/devtools/front_end/TimelinePanel.js
@@ -895,6 +895,12 @@ WebInspector.TimelinePanel.prototype = {
         var startOffset = startTime - this._model.minimumRecordTime();
         var endOffset = endTime - this._model.minimumRecordTime();
         var title = WebInspector.UIString("%s \u2013 %s", Number.millisToString(startOffset), Number.millisToString(endOffset));
+
+        if (Capabilities.canProfilePower) {
+            var powerOverview = /** @type {!WebInspector.TimelinePowerOverview} */ (this._viewsForMode(WebInspector.TimelinePanel.Mode.Power).overviewView);
+            energy = powerOverview.calculateEnergy(startTime, endTime);
+            title += WebInspector.UIString("  Energy: %.2f Joules", energy);
+        }
         this._detailsView.setContent(title, fragment);
     },