From 531906eb8790c11e68f068e6df6816fcc5bb2517 Mon Sep 17 00:00:00 2001
From: Martok <martok@martoks-place.de>
Date: Sat, 21 Jan 2023 22:48:18 +0100
Subject: [PATCH] No issue - add API to tell Profile Timeline Recording state
 to JS engine

Based-on: m-c 1342070/5
---
 docshell/base/timeline/TimelineConsumers.cpp |  7 +++++++
 js/src/jsapi.cpp                             | 14 ++++++++++++++
 js/src/jsapi.h                               | 16 ++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/docshell/base/timeline/TimelineConsumers.cpp b/docshell/base/timeline/TimelineConsumers.cpp
index 92d589c5ba..3abe152881 100644
--- a/docshell/base/timeline/TimelineConsumers.cpp
+++ b/docshell/base/timeline/TimelineConsumers.cpp
@@ -6,6 +6,7 @@
 #include "TimelineConsumers.h"
 
 #include "mozilla/ClearOnShutdown.h"
+#include "jsapi.h"
 #include "nsAppRunner.h" // for XRE_IsContentProcess, XRE_IsParentProcess
 #include "nsDocShell.h"
 
@@ -125,6 +126,9 @@ TimelineConsumers::AddConsumer(nsDocShell* aDocShell)
   UniquePtr<ObservedDocShell>& observed = aDocShell->mObserved;
   MOZ_ASSERT(!observed);
 
+  if (mActiveConsumers == 0) {
+    JS::SetProfileTimelineRecordingEnabled(true);
+  }
   mActiveConsumers++;
 
   ObservedDocShell* obsDocShell = new ObservedDocShell(aDocShell);
@@ -144,6 +148,9 @@ TimelineConsumers::RemoveConsumer(nsDocShell* aDocShell)
   MOZ_ASSERT(observed);
 
   mActiveConsumers--;
+  if (mActiveConsumers == 0) {
+    JS::SetProfileTimelineRecordingEnabled(false);
+  }
 
   // Clear all markers from the `mTimelineMarkers` store.
   observed.get()->ClearMarkers();
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index ca6289344b..7d32948a27 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -1276,6 +1276,20 @@ JS::detail::ComputeThis(JSContext* cx, Value* vp)
     return thisv;
 }
 
+static bool gProfileTimelineRecordingEnabled = false;
+
+JS_PUBLIC_API(void)
+JS::SetProfileTimelineRecordingEnabled(bool enabled)
+{
+    gProfileTimelineRecordingEnabled = enabled;
+}
+
+JS_PUBLIC_API(bool)
+JS::IsProfileTimelineRecordingEnabled()
+{
+    return gProfileTimelineRecordingEnabled;
+}
+
 JS_PUBLIC_API(void*)
 JS_malloc(JSContext* cx, size_t nbytes)
 {
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 0b865ff523..938fcb2a33 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -1545,6 +1545,22 @@ JS_DefineProfilingFunctions(JSContext* cx, JS::HandleObject obj);
 extern JS_PUBLIC_API(bool)
 JS_DefineDebuggerObject(JSContext* cx, JS::HandleObject obj);
 
+namespace JS {
+
+/**
+ * Tell JS engine whether Profile Timeline Recording is enabled or not.
+ * If Profile Timeline Recording is enabled, data shown there like stack won't
+ * be optimized out.
+ * This is global state and not associated with specific runtime or context.
+ */
+extern JS_PUBLIC_API(void)
+SetProfileTimelineRecordingEnabled(bool enabled);
+
+extern JS_PUBLIC_API(bool)
+IsProfileTimelineRecordingEnabled();
+
+} // namespace JS
+
 #ifdef JS_HAS_CTYPES
 /**
  * Initialize the 'ctypes' object on a global variable 'obj'. The 'ctypes'