Bug 1917652 Part 4: Update IPC timing expectations for gpu process platforms. r=mconley,taskgraph-reviewers,jmaher

The message timings that were modified in this test are sent by the
GPUProcessManager, and this test was using WIN and !WIN as a proxy for
whether or not a GPU process was in place. The modifications here make
that more explicit, although they remain approximate. Anything that is
conditioned on GPUPROCESS needs to "ignoreIfUnused" because those
markers will be sent or not sent depending on the presence of the GPU
process, which has complex controls not completely covered by the logic
in this test.

Differential Revision: https://phabricator.services.mozilla.com/D225565

browser/base/content/test/performance/browser_startup_syncIPC.js

@@ -14,6 +14,11 @@ const SKELETONUI = Services.prefs.getBoolPref(
   "browser.startup.preXulSkeletonUI",
   false
 );
+// GPUPROCESS is approximate; any check for this should have "ignoreIfUnused: true".
+const GPUPROCESS =
+  ((WIN || LINUX) &&
+    Services.prefs.getBoolPref("layers.gpu-process.enabled")) ||
+  Services.prefs.getBoolPref("layers.gpu-process.force-enabled");
 
 /*
  * Specifying 'ignoreIfUnused: true' will make the test ignore unused entries;
@@ -52,19 +57,21 @@ const startupPhases = {
     {
       // bug 1373773
       name: "PCompositorBridge::Msg_NotifyChildCreated",
-      condition: !WIN,
+      condition: !GPUPROCESS,
+      ignoreIfUnused: true,
       maxCount: 1,
     },
     {
+      // bug 1373773
       name: "PCompositorBridge::Msg_NotifyChildCreated",
-      condition: WIN,
-      ignoreIfUnused: true, // Only on Win7 32
+      condition: GPUPROCESS,
+      ignoreIfUnused: true,
       maxCount: 2,
     },
     {
       name: "PCompositorBridge::Msg_MapAndNotifyChildCreated",
-      condition: WIN,
-      ignoreIfUnused: true, // Only on Win10 64
+      condition: GPUPROCESS,
+      ignoreIfUnused: true,
       maxCount: 2,
     },
     {
@@ -80,8 +87,8 @@ const startupPhases = {
     },
     {
       name: "PCompositorBridge::Msg_Initialize",
-      condition: WIN,
-      ignoreIfUnused: true, // Only on Win10 64
+      condition: GPUPROCESS,
+      ignoreIfUnused: true,
       maxCount: 3,
     },
     {
@@ -92,8 +99,8 @@ const startupPhases = {
     },
     {
       name: "PGPU::Msg_AddLayerTreeIdMapping",
-      condition: WIN,
-      ignoreIfUnused: true, // Only on Win10 64
+      condition: GPUPROCESS,
+      ignoreIfUnused: true,
       maxCount: 5,
     },
     {
@@ -321,7 +328,7 @@ const startupPhases = {
     // Added for the search-detection built-in add-on.
     {
       name: "PGPU::Msg_AddLayerTreeIdMapping",
-      condition: WIN,
+      condition: GPUPROCESS,
       ignoreIfUnused: true,
       maxCount: 1,
     },