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diff --git a/dom/script/AutoEntryScript.h b/dom/script/AutoEntryScript.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_SCRIPT_AUTOENTRYSCRIPT_H_
+#define DOM_SCRIPT_AUTOENTRYSCRIPT_H_
+
+#include "MainThreadUtils.h"
+#include "js/Debug.h"
+#include "js/TypeDecls.h"
+#include "jsapi.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/dom/JSExecutionManager.h"
+#include "mozilla/dom/ScriptSettings.h"
+
+class nsIGlobalObject;
+class nsIPrincipal;
+
+namespace xpc {
+class AutoScriptActivity;
+}
+
+namespace mozilla::dom {
+
+/*
+ * Static helpers in ScriptSettings which track the number of listeners
+ * of Javascript RunToCompletion events.  These should be used by the code in
+ * nsDocShell::SetRecordProfileTimelineMarkers to indicate to script
+ * settings that script run-to-completion needs to be monitored.
+ * SHOULD BE CALLED ONLY BY MAIN THREAD.
+ */
+void UseEntryScriptProfiling();
+void UnuseEntryScriptProfiling();
+
+/*
+ * A class that represents a new script entry point.
+ *
+ * |aReason| should be a statically-allocated C string naming the reason we're
+ * invoking JavaScript code: "setTimeout", "event", and so on. The devtools use
+ * these strings to label JS execution in timeline and profiling displays.
+ *
+ */
+class MOZ_STACK_CLASS AutoEntryScript : public AutoJSAPI {
+ public:
+  // Constructing the AutoEntryScript will ensure that it enters the
+  // Realm of aGlobalObject's JSObject and exposes that JSObject to active JS.
+  AutoEntryScript(nsIGlobalObject* aGlobalObject, const char* aReason,
+                  bool aIsMainThread = NS_IsMainThread());
+
+  // aObject can be any object from the relevant global. It must not be a
+  // cross-compartment wrapper because CCWs are not associated with a single
+  // global.
+  //
+  // Constructing the AutoEntryScript will ensure that it enters the
+  // Realm of aObject JSObject and exposes aObject's global to active JS.
+  AutoEntryScript(JSObject* aObject, const char* aReason,
+                  bool aIsMainThread = NS_IsMainThread());
+
+  ~AutoEntryScript();
+
+  void SetWebIDLCallerPrincipal(nsIPrincipal* aPrincipal) {
+    mWebIDLCallerPrincipal = aPrincipal;
+  }
+
+ private:
+  // A subclass of AutoEntryMonitor that notifies the docshell.
+  class DocshellEntryMonitor final : public JS::dbg::AutoEntryMonitor {
+   public:
+    DocshellEntryMonitor(JSContext* aCx, const char* aReason);
+
+    // Please note that |aAsyncCause| here is owned by the caller, and its
+    // lifetime must outlive the lifetime of the DocshellEntryMonitor object.
+    // In practice, |aAsyncCause| is identical to |aReason| passed into
+    // the AutoEntryScript constructor, so the lifetime requirements are
+    // trivially satisfied by |aReason| being a statically allocated string.
+    void Entry(JSContext* aCx, JSFunction* aFunction,
+               JS::Handle<JS::Value> aAsyncStack,
+               const char* aAsyncCause) override {
+      Entry(aCx, aFunction, nullptr, aAsyncStack, aAsyncCause);
+    }
+
+    void Entry(JSContext* aCx, JSScript* aScript,
+               JS::Handle<JS::Value> aAsyncStack,
+               const char* aAsyncCause) override {
+      Entry(aCx, nullptr, aScript, aAsyncStack, aAsyncCause);
+    }
+
+    void Exit(JSContext* aCx) override;
+
+   private:
+    void Entry(JSContext* aCx, JSFunction* aFunction, JSScript* aScript,
+               JS::Handle<JS::Value> aAsyncStack, const char* aAsyncCause);
+
+    const char* mReason;
+  };
+
+  // It's safe to make this a weak pointer, since it's the subject principal
+  // when we go on the stack, so can't go away until after we're gone.  In
+  // particular, this is only used from the CallSetup constructor, and only in
+  // the aIsJSImplementedWebIDL case.  And in that case, the subject principal
+  // is the principal of the callee function that is part of the CallArgs just a
+  // bit up the stack, and which will outlive us.  So we know the principal
+  // can't go away until then either.
+  nsIPrincipal* MOZ_NON_OWNING_REF mWebIDLCallerPrincipal;
+  friend nsIPrincipal* GetWebIDLCallerPrincipal();
+
+  Maybe<DocshellEntryMonitor> mDocShellEntryMonitor;
+  Maybe<xpc::AutoScriptActivity> mScriptActivity;
+  JS::AutoHideScriptedCaller mCallerOverride;
+  AutoProfilerLabel mAutoProfilerLabel;
+  AutoRequestJSThreadExecution mJSThreadExecution;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // DOM_SCRIPT_AUTOENTRYSCRIPT_H_