Bug 1945944: Add layout debugger startup option to turn on deterministic frame dumping by default. r=layout-reviewers,emilio

Differential Revision: https://phabricator.services.mozilla.com/D236874

layout/tools/layout-debug/src/nsLayoutDebugCLH.cpp

@@ -104,6 +104,7 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
   bool captureProfile = false;
   nsString profileFilename;
   bool paged = false;
+  bool deterministicFrameDumping = false;
 
   rv = HandleFlagWithOptionalArgument(aCmdLine, u"layoutdebug"_ns,
                                       u"about:blank"_ns, url, flagPresent);
@@ -125,6 +126,10 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
   rv = aCmdLine->HandleFlag(u"paged"_ns, false, &paged);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  rv = aCmdLine->HandleFlag(u"deterministic-frame-dumping"_ns, false,
+                            &deterministicFrameDumping);
+  NS_ENSURE_SUCCESS(rv, rv);
+
   nsCOMPtr<nsIMutableArray> argsArray = nsArray::Create();
 
   nsCOMPtr<nsIURI> uri;
@@ -161,6 +166,11 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
+  if (deterministicFrameDumping) {
+    rv = AppendArg(argsArray, u"deterministic-frame-dumping"_ns);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
   nsCOMPtr<nsIWindowWatcher> wwatch =
       do_GetService(NS_WINDOWWATCHER_CONTRACTID);
   NS_ENSURE_TRUE(wwatch, NS_ERROR_FAILURE);
@@ -184,6 +194,9 @@ nsLayoutDebugCLH::GetHelpInfo(nsACString& aResult) {
       "                     Debugger using the Gecko Profiler, and save the\n"
       "                     profile to the specified file (which defaults to\n"
       "                     profile.json).\n"
-      "  --paged Layout the page in paginated mode.\n");
+      "  --paged Layout the page in paginated mode.\n"
+      "  --deterministic-frame-dumping Toggle option to only include\n"
+      "                                deterministic information in frame dumps,\n"
+      "                                for ease of diffing.\n");
   return NS_OK;
 }

layout/tools/layout-debug/ui/content/layoutdebug.js

@@ -298,6 +298,7 @@ function parseArguments() {
     autoclose: false,
     delay: 0,
     paged: false,
+    deterministicFrameDumping: false,
   };
   if (window.arguments) {
     args.url = window.arguments[0];
@@ -311,6 +312,8 @@ function parseArguments() {
         args.profileFilename = RegExp.$1;
       } else if (/^paged$/.test(arg)) {
         args.paged = true;
+      } else if (/^deterministic-frame-dumping$/.test(arg)) {
+        args.deterministicFrameDumping = true;
       } else {
         throw `Unknown option ${arg}`;
       }
@@ -397,6 +400,8 @@ function OnLDBLoad() {
     loadStringURI(gArgs.url);
   }
 
+  gDebugger._deterministicFrameDumping = gArgs.deterministicFrameDumping;
+
   // Some command line arguments may toggle menu items. Call this after
   // processing all the arguments.
   checkPersistentMenus();
@@ -416,6 +421,7 @@ function checkPersistentMenus() {
   checkPersistentMenu("crossingEventDumping");
   checkPersistentMenu("reflowCounts");
   checkPersistentMenu("pagedMode");
+  checkPersistentMenu("deterministicFrameDumping");
 }
 
 function dumpProfile() {