[Perf panel] Remove support for experimental server timings track

We did not receive clear signal about the usefulness of having a mechanism to display server timings in the client timeline.

Developers will still be able to see server timings in the details of network requests (as of https://crrev.com/c/6387100) and if needed, a server timing track could be injected using the extensibility API. (granted, a mechanisim to map server timestamps to the client clock needs to be implemented, but this doesn't seem to be a big constraint as devs are alreading doing so, like React).

Bug: 403223638
Change-Id: I10d80fe10598dcf7c3014cfc1fcbce03b6024fb5
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6387102
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Andres Olivares <andoli@chromium.org>

Author: and-oli

config/gni/devtools_grd_files.gni

@@ -1146,7 +1146,6 @@ grd_files_debug_sources = [
   "front_end/models/trace/handlers/ScreenshotsHandler.js",
   "front_end/models/trace/handlers/ScriptsHandler.js",
   "front_end/models/trace/handlers/SelectorStatsHandler.js",
-  "front_end/models/trace/handlers/ServerTimingsHandler.js",
   "front_end/models/trace/handlers/Threads.js",
   "front_end/models/trace/handlers/UserInteractionsHandler.js",
   "front_end/models/trace/handlers/UserTimingsHandler.js",
@@ -1866,7 +1865,6 @@ grd_files_debug_sources = [
   "front_end/panels/timeline/ModificationsManager.js",
   "front_end/panels/timeline/NetworkTrackAppender.js",
   "front_end/panels/timeline/SaveFileFormatter.js",
-  "front_end/panels/timeline/ServerTimingsTrackAppender.js",
   "front_end/panels/timeline/TargetForEvent.js",
   "front_end/panels/timeline/ThirdPartyTreeView.js",
   "front_end/panels/timeline/ThreadAppender.js",

front_end/core/host/UserMetrics.ts

@@ -979,7 +979,6 @@ export enum DevtoolsExperiments {
   'timeline-enhanced-traces' = 90,
   'timeline-compiled-sources' = 91,
   'timeline-debug-mode' = 93,
-  'timeline-server-timings' = 98,
   'timeline-experimental-insights' = 102,
   'timeline-dim-unrelated-events' = 103,
   'timeline-alternative-navigation' = 104,

front_end/core/root/Runtime.ts

@@ -321,7 +321,6 @@ export const enum ExperimentName {
   TIMELINE_DEBUG_MODE = 'timeline-debug-mode',
   TIMELINE_ENHANCED_TRACES = 'timeline-enhanced-traces',
   TIMELINE_COMPILED_SOURCES = 'timeline-compiled-sources',
-  TIMELINE_SERVER_TIMINGS = 'timeline-server-timings',
   TIMELINE_EXPERIMENTAL_INSIGHTS = 'timeline-experimental-insights',
   TIMELINE_DIM_UNRELATED_EVENTS = 'timeline-dim-unrelated-events',
   TIMELINE_ALTERNATIVE_NAVIGATION = 'timeline-alternative-navigation',

front_end/entrypoints/main/MainImpl.ts

@@ -369,11 +369,6 @@ export class MainImpl {
         'Performance panel: show postMessage dispatch and handling flows',
     );
 
-    Root.Runtime.experiments.register(
-        Root.Runtime.ExperimentName.TIMELINE_SERVER_TIMINGS,
-        'Performance panel: enable server timings in the timeline',
-    );
-
     Root.Runtime.experiments.register(
         Root.Runtime.ExperimentName.TIMELINE_EXPERIMENTAL_INSIGHTS,
         'Performance panel: enable experimental performance insights',

front_end/models/trace/handlers/BUILD.gn

@@ -36,7 +36,6 @@ devtools_module("handlers") {
     "ScreenshotsHandler.ts",
     "ScriptsHandler.ts",
     "SelectorStatsHandler.ts",
-    "ServerTimingsHandler.ts",
     "Threads.ts",
     "UserInteractionsHandler.ts",
     "UserTimingsHandler.ts",
@@ -97,7 +96,6 @@ ts_library("unittests") {
     "ScreenshotsHandler.test.ts",
     "ScriptsHandler.test.ts",
     "SelectorStatsHandler.test.ts",
-    "ServerTimingsHandler.test.ts",
     "Threads.test.ts",
     "UserInteractionsHandler.test.ts",
     "UserTimingsHandler.test.ts",

front_end/models/trace/handlers/ModelHandlers.ts

@@ -28,7 +28,6 @@ export * as Samples from './SamplesHandler.js';
 export * as Screenshots from './ScreenshotsHandler.js';
 export * as Scripts from './ScriptsHandler.js';
 export * as SelectorStats from './SelectorStatsHandler.js';
-export * as ServerTimings from './ServerTimingsHandler.js';
 export * as UserInteractions from './UserInteractionsHandler.js';
 export * as UserTimings from './UserTimingsHandler.js';
 export * as Warnings from './WarningsHandler.js';

front_end/models/trace/handlers/ServerTimingsHandler.test.ts

@@ -50,12 +50,6 @@ export class SyntheticEventsManager {
     }
   }
 
-  static registerServerTiming(syntheticEvent: Omit<Types.Events.SyntheticServerTiming, '_tag'>):
-      Types.Events.SyntheticServerTiming {
-    // TODO(crbug.com/340811171): Implement
-    return syntheticEvent as Types.Events.SyntheticServerTiming;
-  }
-
   private constructor(rawEvents: readonly Types.Events.Event[]) {
     this.#rawTraceEvents = rawEvents;
   }

front_end/models/trace/handlers/ServerTimingsHandler.ts

@@ -402,7 +402,6 @@ export interface SyntheticNetworkRequest extends Complete, SyntheticBased<Phase.
       initiator?: Initiator,
       requestMethod?: string,
       timing?: ResourceReceiveResponseTimingData,
-      syntheticServerTimings?: SyntheticServerTiming[],
     },
   };
   cat: 'loading';
@@ -1645,25 +1644,6 @@ export interface SyntheticProfileCall extends Event {
   profileId: ProfileID;
 }
 
-/**
- * A synthetic event created from the Server-Timing header of network
- * request. In order to create these synthetic events, the corresponding
- * metric (timing) in the header must contain a "start" param, which
- * corresponds to the timestamp of the metric in the server. The
- * ServerTimingsHandler implements a heuristic to estimate the offset
- * between the client clock and the server clock so that the server
- * timestamp can be translated to the tracing clock.
- */
-export interface SyntheticServerTiming<T extends Phase = Phase.COMPLETE> extends SyntheticBased<T> {
-  rawSourceEvent: ResourceSendRequest;
-  cat: 'devtools.server-timing';
-  args: Args&{
-    data: ArgsData & {
-      desc?: string, origin: string,
-    },
-  };
-}
-
 /**
  * A JS Sample reflects a single sample from the V8 CPU Profile
  */
@@ -2736,10 +2716,6 @@ export function isFunctionCall(event: Event): event is FunctionCall {
   return event.name === Name.FUNCTION_CALL;
 }
 
-export function isSyntheticServerTiming(event: Event): event is SyntheticServerTiming {
-  return event.cat === 'devtools.server-timing';
-}
-
 export interface SchedulePostTaskCallback extends Instant {
   name: Name.SCHEDULE_POST_TASK_CALLBACK;
   args: Args&{