Initialize min/max record time to 0 instead of -1 or null

This simplifies many boundary time computations all around the code.

BUG=361045

Review URL: https://codereview.chromium.org/322783002

git-svn-id: svn://svn.chromium.org/blink/trunk@175801 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -131,7 +131,7 @@ WebInspector.TimelineFlameChartDataProvider.prototype = {
 
         this._records = [];
         this._entryThreadDepths = {};
-        this._minimumBoundary = Math.max(0, this._model.minimumRecordTime());
+        this._minimumBoundary = this._model.minimumRecordTime();
 
         var cpuThreadRecordPayload = { type: WebInspector.TimelineModel.RecordType.Program };
         this._cpuThreadRecord = new WebInspector.TimelineModel.RecordImpl(this._model, /** @type {!TimelineAgent.TimelineEvent} */ (cpuThreadRecordPayload), null);
@@ -549,8 +549,8 @@ WebInspector.TracingBasedTimelineFlameChartDataProvider.prototype = {
         };
 
         this._currentLevel = 0;
-        this._minimumBoundary = this._model.minimumRecordTime() || 0;
-        this._timeSpan = Math.max((this._model.maximumRecordTime() || 0) - this._minimumBoundary, 1000000);
+        this._minimumBoundary = this._model.minimumRecordTime();
+        this._timeSpan = Math.max(this._model.maximumRecordTime() - this._minimumBoundary, 1000);
         this._appendHeaderRecord("CPU");
         var events = this._model.mainThreadEvents();
         var maxStackDepth = 0;

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

@@ -251,8 +251,8 @@ WebInspector.TimelineModel.prototype = {
     {
         this._loadedFromFile = false;
         this._records = [];
-        this._minimumRecordTime = -1;
-        this._maximumRecordTime = -1;
+        this._minimumRecordTime = 0;
+        this._maximumRecordTime = 0;
         /** @type {!Array.<!WebInspector.TimelineModel.Record>} */
         this._mainThreadTasks =  [];
         /** @type {!Array.<!WebInspector.TimelineModel.Record>} */
@@ -286,9 +286,9 @@ WebInspector.TimelineModel.prototype = {
         var startTime = record.startTime();
         var endTime = record.endTime();
 
-        if (this._minimumRecordTime === -1 || startTime < this._minimumRecordTime)
+        if (!this._minimumRecordTime || startTime < this._minimumRecordTime)
             this._minimumRecordTime = startTime;
-        if ((this._maximumRecordTime === -1 && endTime) || endTime > this._maximumRecordTime)
+        if (endTime > this._maximumRecordTime)
             this._maximumRecordTime = endTime;
     },
 

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

@@ -409,7 +409,7 @@ WebInspector.TimelineOverviewBase.prototype = {
     {
         var absoluteMin = this._model.minimumRecordTime();
         var timeSpan = this._model.maximumRecordTime() - absoluteMin;
-        var haveRecords = absoluteMin >= 0;
+        var haveRecords = absoluteMin > 0;
         return {
             left: haveRecords && startTime ? Math.min((startTime - absoluteMin) / timeSpan, 1) : 0,
             right: haveRecords && endTime < Infinity ? (endTime - absoluteMin) / timeSpan : 1

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

@@ -202,10 +202,7 @@ WebInspector.TimelinePanel.prototype = {
     {
         if (this._windowStartTime)
             return this._windowStartTime;
-        var minimumRecordTime = this._model.minimumRecordTime();
-        if (minimumRecordTime && minimumRecordTime !== -1)
-            return minimumRecordTime;
-        return 0;
+        return this._model.minimumRecordTime();
     },
 
     /**
@@ -215,10 +212,7 @@ WebInspector.TimelinePanel.prototype = {
     {
         if (this._windowEndTime < Infinity)
             return this._windowEndTime;
-        var maximumRecordTime = this._model.maximumRecordTime();
-        if (maximumRecordTime && maximumRecordTime !== -1)
-            return maximumRecordTime;
-        return Infinity;
+        return this._model.maximumRecordTime() || Infinity;
     },
 
     /**

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

@@ -316,7 +316,7 @@ WebInspector.TraceViewFlameChartDataProvider.prototype = {
         this._currentLevel = 0;
         this._headerTitles = {};
         this._minimumBoundary = this._timelineModelForMinimumBoundary.minimumRecordTime();
-        this._timeSpan = Math.max((this._model.maximumRecordTime() || 0) - this._minimumBoundary, 1000);
+        this._timeSpan = Math.max(this._model.maximumRecordTime() - this._minimumBoundary, 1000);
         var processes = this._model.sortedProcesses();
         for (var processIndex = 0; processIndex < processes.length; ++processIndex) {
             var process = processes[processIndex];

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

@@ -248,8 +248,8 @@ WebInspector.TimelineView.prototype = {
 
     _resetView: function()
     {
-        this._windowStartTime = -1;
-        this._windowEndTime = -1;
+        this._windowStartTime = 0;
+        this._windowEndTime = 0;
         this._boundariesAreValid = false;
         this._adjustScrollPosition(0);
         this._linkifier.reset();
@@ -456,13 +456,9 @@ WebInspector.TimelineView.prototype = {
             clearTimeout(this._refreshTimeout);
             delete this._refreshTimeout;
         }
-        var windowStartTime = this._windowStartTime;
-        var windowEndTime = this._windowEndTime;
+        var windowStartTime = this._windowStartTime || this._model.minimumRecordTime();
+        var windowEndTime = this._windowEndTime || this._model.maximumRecordTime();
         this._timelinePaddingLeft = this._expandOffset;
-        if (windowStartTime === -1)
-            windowStartTime = this._model.minimumRecordTime();
-        if (windowEndTime === -1)
-            windowEndTime = this._model.maximumRecordTime();
         this._calculator.setWindow(windowStartTime, windowEndTime);
         this._calculator.setDisplayWindow(this._timelinePaddingLeft, this._graphRowsElementWidth);
 

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

@@ -168,8 +168,8 @@ WebInspector.TracingModel.prototype = {
     reset: function()
     {
         this._processById = {};
-        this._minimumRecordTime = null;
-        this._maximumRecordTime = null;
+        this._minimumRecordTime = 0;
+        this._maximumRecordTime = 0;
         this._sessionId = null;
         this._devtoolsMetadataEvents = [];
     },
@@ -222,7 +222,7 @@ WebInspector.TracingModel.prototype = {
     },
 
     /**
-     * @return {?number}
+     * @return {number}
      */
     minimumRecordTime: function()
     {
@@ -230,7 +230,7 @@ WebInspector.TracingModel.prototype = {
     },
 
     /**
-     * @return {?number}
+     * @return {number}
      */
     maximumRecordTime: function()
     {

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

@@ -169,7 +169,7 @@ WebInspector.TracingTimelineModel.prototype = {
     },
 
     /**
-     * @return {?number}
+     * @return {number}
      */
     minimumRecordTime: function()
     {
@@ -177,7 +177,7 @@ WebInspector.TracingTimelineModel.prototype = {
     },
 
     /**
-     * @return {?number}
+     * @return {number}
      */
     maximumRecordTime: function()
     {