DevTools: Support reading CPU profile format on Performance panel

third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js

Index: third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js
index 3769b458206fb47843b5be5d5f012f2853414874..bf9149848bc6857c882d4557b03f1e292fef0d9b 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js
+++ b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineJSProfile.js
@@ -231,6 +231,93 @@ TimelineModel.TimelineJSProfileProcessor = class {
     }
     return map.get(nativeName) || null;
   }
+
+  /**
+   * @param {*} profile

[caseq, 2017/03/02 19:00:40]

?Object

[alph, 2017/03/02 19:20:00]

This actually could be anything, as it comes out of JSON.parse.
We handle bad cases with try-catch.

+   * @return {!Array<!SDK.TracingManager.EventPayload>}
+   */
+  static buildTraceProfileFromCpuProfile(profile) {
+    if (!profile)
+      return [];
+    var start = profile.startTime;
+    var events = [];
+    appendEvent('TracingStartedInPage', {'sessionId': '1'}, 0, 0, 'M');
+    var idToNode = new Map();
+    for (var i = 0; i < profile.nodes.length; ++i)

[caseq, 2017/03/02 19:00:40]

profile['nodes']...

[alph, 2017/03/02 19:20:00]

Done.

+      idToNode.set(profile.nodes[i].id, profile.nodes[i]);
+    var stateProgram = '(program)';
+    var stateIdle = '(idle)';
+    var stateFunction = '(function)';
+    var state = stateIdle;
+    var programEvent = null;
+    var functionEvent = null;
+    var nextTime = start;
+    for (var i = 0; i < profile.samples.length; ++i) {
+      var currentTime = nextTime;
+      nextTime += profile.timeDeltas[i];
+      var id = profile.samples[i];
+      var node = idToNode.get(id);
+      var name = node.callFrame.functionName;
+      if (state === name)

[caseq, 2017/03/02 19:00:40]

Let's keep the state space separate from names space (like automatons that have
input alphabet separate from state set).

[alph, 2017/03/02 19:20:00]

Done.

+        continue;
+      if (state === stateIdle) {
+        programEvent = appendEvent('MessageLoop::RunTask', {}, currentTime, 0, 'X', 'toplevel');
+        state = stateProgram;
+        if (name !== '(program)') {
+          functionEvent = appendEvent('FunctionCall', {'sessionId': '1'}, currentTime, 0);
+          state = stateFunction;
+        }
+        continue;
+      }
+      if (name === stateIdle) {
+        if (programEvent)
+          programEvent.dur = currentTime - programEvent.ts;
+        if (functionEvent)
+          functionEvent.dur = currentTime - functionEvent.ts;
+        programEvent = null;
+        functionEvent = null;
+        state = stateIdle;
+        continue;
+      }
+      // Remaining cases program->function and function->program.
+      if (name === stateProgram) {
+        functionEvent.dur = currentTime - functionEvent.ts;
+        functionEvent = null;
+        state = stateProgram;
+      } else if (state === stateProgram) {
+        functionEvent = appendEvent('FunctionCall', {'sessionId': '1'}, currentTime, 0);
+        state = stateFunction;
+      }
+    }
+    appendEvent('CpuProfile', {'cpuProfile': profile}, profile.endTime, 0, 'I');
+    events.sort((a, b) => a.startTime - b.startTime);
+    return events;
+
+    /**
+     * @param {string} name
+     * @param {*} data
+     * @param {number} ts
+     * @param {number=} dur
+     * @param {string=} ph
+     * @param {string=} cat
+     * @return {!SDK.TracingManager.EventPayload}
+     */
+    function appendEvent(name, data, ts, dur, ph, cat) {
+      var event = /** @type {!SDK.TracingManager.EventPayload} */ ({
+        cat: cat || 'disabled-by-default-devtools.timeline',
+        name: name,
+        ph: ph || 'X',
+        pid: 1,
+        tid: 1,
+        ts: ts,
+        args: {data: data}
+      });
+      if (dur)
+        event.dur = dur;
+      events.push(event);
+      return event;
+    }
+  }
 };
 
 /** @enum {string} */