DevTools: Do not show network pane on Timeline when there're no network activity

third_party/WebKit/Source/devtools/front_end/timeline/TimelineNetworkFlameChart.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @implements {UI.FlameChartDataProvider}
  * @unrestricted
  */
 Timeline.TimelineFlameChartNetworkDataProvider = class {
   /**
    * @param {!TimelineModel.TimelineModel} model
    */
   constructor(model) {
-    this.reset();
     this._font = '11px ' + Host.fontFamily();
     this._model = model;
-    var loadingCategory = Timeline.TimelineUIUtils.categories()['loading'];
-    this._waitingColor = loadingCategory.childColor;
-    this._processingColor = loadingCategory.color;
-
+    this.reset();
     this._style = {
       padding: 4,
       height: 17,
       collapsible: true,
       color: UI.themeSupport.patchColor('#222', UI.ThemeSupport.ColorUsage.Foreground),
       font: this._font,
       backgroundColor: UI.themeSupport.patchColor('white', UI.ThemeSupport.ColorUsage.Background),
       nestingLevel: 0,
       useFirstLineForOverview: false,
       shareHeaderLine: false
     };
     this._group = {startLevel: 0, name: Common.UIString('Network'), expanded: true, style: this._style};
   }
 
   /**
+   * @return {boolean}
+   */
+  isEmpty() {
+    this.timelineData();
+    return this._maxLevel === 0;
+  }
+
+  /**
    * @override
    * @return {number}
    */
   maxStackDepth() {
     return this._maxLevel;
   }
 
   /**
    * @override
    * @return {!UI.FlameChart.TimelineData}
@@ skipping 296 matching lines @@
     this._requests.push(request);
     this._timelineData.entryStartTimes.push(request.startTime);
     this._timelineData.entryTotalTimes.push(request.endTime - request.startTime);
     this._timelineData.entryLevels.push(this._requests.length - 1);
   }
 
   /**
    * @return {number}
    */
   preferredHeight() {
-    return this._style.height * (this._group.expanded ? Number.constrain(this._maxLevel + 1, 4, 8) : 2);
+    return this._style.height * (this._group.expanded ? Number.constrain(this._maxLevel + 1, 4, 8.5) : 1);
   }
 
   /**
    * @override
    * @param {number} value
    * @param {number=} precision
    * @return {string}
    */
   formatValue(value, precision) {
     return Number.preciseMillisToString(value, precision);
   }
 
   /**
    * @override
    * @param {number} entryIndex
    * @return {boolean}
    */
   canJumpToEntry(entryIndex) {
     return false;
   }
 };