core(tracing): handle FrameCommittedInBrowser with processPseudoId

core/lib/tracehouse/trace-processor.js

@@ -489,20 +489,22 @@ class TraceProcessor {
    */
   static findMainFramePidTids(mainFrameInfo, keyEvents) {
     const frameCommittedEvts = keyEvents.filter(evt =>
-      evt.name === 'FrameCommittedInBrowser' &&
+      // ProcessReadyInBrowser is used when a processID isn't available when the FrameCommittedInBrowser trace event is emitted.
+      // In that case. FrameCommittedInBrowser has no processId, but a processPseudoId. and the ReadyInBrowser event declares the proper processId.
+      (evt.name === 'FrameCommittedInBrowser' || evt.name === 'ProcessReadyInBrowser') &&
       evt.args?.data?.frame === mainFrameInfo.frameId
     );
 
     // "Modern" traces with a navigation have a FrameCommittedInBrowser event
     const mainFramePids = frameCommittedEvts.length
-      ? frameCommittedEvts.map(e => e?.args?.data?.processId)
+      ? frameCommittedEvts.map(e => e?.args?.data?.processId).filter(Boolean)
       // …But old traces and some timespan traces may not. In these situations, we'll assume the
       // primary process ID remains constant (as there were no navigations).
       : [mainFrameInfo.startingPid];
 
     const pidToTid = new Map();
 
-    mainFramePids.forEach(pid => {
+    Array.from(new Set(mainFramePids)).forEach(pid => {
       // While renderer tids are generally predictable, we'll doublecheck it
       const threadNameEvt = keyEvents.find(e =>
         e.cat === '__metadata' &&
@@ -712,7 +714,8 @@ class TraceProcessor {
     }
     const frameEvents = keyEvents.filter(e => associatedToMainFrame(e));
 
-    // Filter to just events matching the main frame ID or any child frame IDs.
+    // Filter to just events matching the main frame ID or any child frame IDs. The subframes
+    // are either in-process (same origin) or, potentially, out-of-process. (OOPIFs)
     let frameTreeEvents = [];
     if (frameIdToRootFrameId.has(mainFrameInfo.frameId)) {
       frameTreeEvents = keyEvents.filter(e => associatedToAllFrames(e));

core/test/lib/tracehouse/trace-processor-test.js

@@ -23,6 +23,7 @@ const lcpTrace = readJson('../../fixtures/traces/lcp-m78.json', import.meta);
 const lcpAllFramesTrace = readJson('../../fixtures/traces/frame-metrics-m89.json', import.meta);
 const startedAfterNavstartTrace = readJson('../../fixtures/traces/tracingstarted-after-navstart.json', import.meta);
 const pidChangeTrace = readJson('../../fixtures/traces/pid-change.json', import.meta);
+const decentlyModernTrace = readJson('../../fixtures/traces/frame-metrics-m90.json', import.meta);
 
 describe('TraceProcessor', () => {
   describe('_riskPercentiles', () => {
@@ -943,10 +944,8 @@ Object {
       const mainFramePids = new Set();
       mainFramePids.add(processed.mainFrameInfo.startingPid);
       [...processed._rendererPidToTid.keys()].forEach(pid => mainFramePids.add(pid));
-
       return {processEventsPct, frameEventsPct, mainFramePids};
     }
-
     // Single PID trace
     const lcpTraceSummarized = summarizeTrace(lcpTrace);
     expect(lcpTraceSummarized.mainFramePids.size).toEqual(1);
@@ -964,5 +963,33 @@ Object {
     // The main frame's events should make up more than 40% of all key trace events
     // TODO: fix!
     // expect(pidChangeTraceSummarized.frameEventsPct).toBeGreaterThanOrEqual(0.4);
+
+
+    // FrameCommittedInBrowser w/o processId, but w/ processPsuedoId, and later a ProcessReadyInBrowser
+    //
+    // A 'normal' FrameCommittedInBrowser's data is:
+    //                 {"frame":"FRAME_ID","name":"","processId":72647,"url":"https://memegen.corp.google.com/"}
+    // But if the processId isn't ready at frame creation, we get this pair:
+    // {"args":{"data":{"frame":"FRAME_ID","name":"","processPseudoId":"0x7ff70022ca00","url":"https://memegen.com/"}},"cat":"disabled-by-default-devtools.timeline","name":"FrameCommittedInBrowser","ph":"I","pid":744,"s":"t","tid":775,"ts":123265406529,"tts":10824502153},
+    // {"args":{"data":{"frame":"FRAME_ID","processId":72647,"processPseudoId":"0x7ff70022ca00"}},"cat":"disabled-by-default-devtools.timeline","name":"ProcessReadyInBrowser","ph":"I","pid":744,"s":"t","tid":775,"ts":123265450207,"tts":10824519750},
+
+    {
+      const psuedoProcTrace = JSON.parse(JSON.stringify(decentlyModernTrace));
+      const fcibEvt = psuedoProcTrace.traceEvents.find(e => e.name === 'FrameCommittedInBrowser');
+      const {url, processId, frame, name} = fcibEvt.args.data;
+      expect(processId).toBeTruthy();
+      fcibEvt.args.data = {frame, name, url, processPseudoId: '0xbaabaa'};
+
+      const procReadyEvt = JSON.parse(JSON.stringify(fcibEvt));
+      procReadyEvt.name = 'ProcessReadyInBrowser';
+      procReadyEvt.args.data = {frame, processId, processPseudoId: '0xbaabaa'};
+      procReadyEvt.ts = fcibEvt.ts + 10;
+      psuedoProcTrace.traceEvents.push(procReadyEvt);
+
+      const psuedoProcSummarized = summarizeTrace(psuedoProcTrace);
+      expect(psuedoProcSummarized.mainFramePids.size).toEqual(1);
+      // The primary process events should make up more than 40% of all key trace events
+      expect(psuedoProcSummarized.processEventsPct).toBeGreaterThanOrEqual(0.4);
+    }
   });
 });