DevTools: Make DevTools performance work for ndb

Do not generate multiple TracingStatedInPage events. It was causing N^2 passes
over CPU profiles slowing down execution and consuming lots of memory.

Change-Id: Id8c3293a7cc92a2cc611746f68c92a2c9a0b63f6
Reviewed-on: https://chromium-review.googlesource.com/1179239
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583940}

third_party/blink/renderer/devtools/front_end/timeline/TimelineController.js

@@ -302,16 +302,12 @@ Timeline.TimelineController = class {
       } else {
         // Or there was no tracing manager in the main target at all, in this case build the model full
         // of cpu profiles.
-        // Assign tids equal to the target ordinals for the thread name lookup.
-        // This is a little shaky because targets can disappear, but we will read these tids sooner than
-        // that.
-        // TODO(pfeldman): resolve this.
-        let counter = 1000;
+        let tid = 0;
         for (const pair of this._cpuProfiles) {
           const target = SDK.targetManager.targetById(pair[0]);
-          const tid = target ? SDK.targetManager.targets().indexOf(target) : ++counter;
-          this._tracingModel.addEvents(
-              TimelineModel.TimelineJSProfileProcessor.buildTraceProfileFromCpuProfile(pair[1], tid));
+          const name = target && target.name();
+          this._tracingModel.addEvents(TimelineModel.TimelineJSProfileProcessor.buildTraceProfileFromCpuProfile(
+              pair[1], ++tid, /* injectPageEvent */ tid === 1, name));
         }
       }
     }

third_party/blink/renderer/devtools/front_end/timeline/TimelineLoader.js

@@ -221,7 +221,8 @@ Timeline.TimelineLoader = class {
     let traceEvents;
     try {
       const profile = JSON.parse(text);
-      traceEvents = TimelineModel.TimelineJSProfileProcessor.buildTraceProfileFromCpuProfile(profile, 1);
+      traceEvents = TimelineModel.TimelineJSProfileProcessor.buildTraceProfileFromCpuProfile(
+          profile, /* tid */ 1, /* injectPageEvent */ true);
     } catch (e) {
       this._reportErrorAndCancelLoading(Common.UIString('Malformed CPU profile format'));
       return;

third_party/blink/renderer/devtools/front_end/timeline_model/TimelineJSProfile.js

@@ -228,13 +228,19 @@ TimelineModel.TimelineJSProfileProcessor = class {
   /**
    * @param {*} profile
    * @param {number} tid
+   * @param {boolean} injectPageEvent
+   * @param {?string=} name
    * @return {!Array<!SDK.TracingManager.EventPayload>}
    */
-  static buildTraceProfileFromCpuProfile(profile, tid) {
-    if (!profile)
-      return [];
+  static buildTraceProfileFromCpuProfile(profile, tid, injectPageEvent, name) {
     const events = [];
-    appendEvent('TracingStartedInPage', {'sessionId': '1'}, 0, 0, 'M');
+    if (injectPageEvent)
+      appendEvent('TracingStartedInPage', {data: {'sessionId': '1'}}, 0, 0, 'M');
+    if (!name)
+      name = ls`Thread ${tid}`;
+    appendEvent(SDK.TracingModel.MetadataEvent.ThreadName, {name}, 0, 0, 'M', '__metadata');
+    if (!profile)
+      return events;
     const idToNode = new Map();
     const nodes = profile['nodes'];
     for (let i = 0; i < nodes.length; ++i)
@@ -264,11 +270,11 @@ TimelineModel.TimelineJSProfileProcessor = class {
       } else {
         // A JS function.
         if (!functionEvent)
-          functionEvent = appendEvent('FunctionCall', {'sessionId': '1'}, currentTime);
+          functionEvent = appendEvent('FunctionCall', {data: {'sessionId': '1'}}, currentTime);
       }
     }
     closeEvents();
-    appendEvent('CpuProfile', {'cpuProfile': profile}, profile.endTime, 0, 'I');
+    appendEvent('CpuProfile', {data: {'cpuProfile': profile}}, profile.endTime, 0, 'I');
     return events;
 
     function closeEvents() {
@@ -282,23 +288,16 @@ TimelineModel.TimelineJSProfileProcessor = class {
 
     /**
      * @param {string} name
-     * @param {*} data
+     * @param {*} args
      * @param {number} ts
      * @param {number=} dur
      * @param {string=} ph
      * @param {string=} cat
      * @return {!SDK.TracingManager.EventPayload}
      */
-    function appendEvent(name, data, ts, dur, ph, cat) {
-      const event = /** @type {!SDK.TracingManager.EventPayload} */ ({
-        cat: cat || 'disabled-by-default-devtools.timeline',
-        name: name,
-        ph: ph || 'X',
-        pid: 1,
-        tid,
-        ts: ts,
-        args: {data: data}
-      });
+    function appendEvent(name, args, ts, dur, ph, cat) {
+      const event = /** @type {!SDK.TracingManager.EventPayload} */ (
+          {cat: cat || 'disabled-by-default-devtools.timeline', name, ph: ph || 'X', pid: 1, tid, ts, args});
       if (dur)
         event.dur = dur;
       events.push(event);

third_party/blink/renderer/devtools/front_end/timeline_model/TimelineModel.js

@@ -201,6 +201,8 @@ TimelineModel.TimelineModel = class {
       const metaEvent = metadataEvents.page[i];
       const process = metaEvent.thread.process();
       const endTime = i + 1 < length ? metadataEvents.page[i + 1].startTime : Infinity;
+      if (startTime === endTime)
+        continue;
       this._legacyCurrentPage = metaEvent.args['data'] && metaEvent.args['data']['page'];
       for (const thread of process.sortedThreads()) {
         let workerUrl = null;