From ec372faefedd1932f45b2135122ad4bb306f2c7c Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 10 Mar 2021 08:52:19 -0500
Subject: [PATCH] Remove DevTools dependency on Scheduler runWithPriority
 (#20967)

---
 .../devtools/views/Components/TreeContext.js  | 15 ++----
 .../src/app/PriorityLevels/index.js           | 54 -------------------
 .../react-devtools-shell/src/app/index.js     |  2 -
 3 files changed, 5 insertions(+), 66 deletions(-)
 delete mode 100644 packages/react-devtools-shell/src/app/PriorityLevels/index.js

diff --git a/packages/react-devtools-shared/src/devtools/views/Components/TreeContext.js b/packages/react-devtools-shared/src/devtools/views/Components/TreeContext.js
index a824bd493ff84..0ab6e57c4b414 100644
--- a/packages/react-devtools-shared/src/devtools/views/Components/TreeContext.js
+++ b/packages/react-devtools-shared/src/devtools/views/Components/TreeContext.js
@@ -34,12 +34,8 @@ import {
   useMemo,
   useReducer,
   useRef,
+  unstable_startTransition as startTransition,
 } from 'react';
-import {
-  unstable_next as next,
-  unstable_runWithPriority as runWithPriority,
-  unstable_UserBlockingPriority as UserBlockingPriority,
-} from 'scheduler';
 import {createRegExp} from '../utils';
 import {BridgeContext, StoreContext} from '../context';
 import Store from '../../store';
@@ -923,11 +919,10 @@ function TreeContextController({
 
   const dispatchWrapper = useCallback(
     (action: Action) => {
-      // Run the first update at "user-blocking" priority in case dispatch is called from a non-React event.
-      // In this case, the current (and "next") priorities would both be "normal",
-      // and suspense would potentially block both updates.
-      runWithPriority(UserBlockingPriority, () => dispatch(action));
-      next(() => dispatch({type: 'UPDATE_INSPECTED_ELEMENT_ID'}));
+      dispatch(action);
+      startTransition(() => {
+        dispatch({type: 'UPDATE_INSPECTED_ELEMENT_ID'});
+      });
     },
     [dispatch],
   );
diff --git a/packages/react-devtools-shell/src/app/PriorityLevels/index.js b/packages/react-devtools-shell/src/app/PriorityLevels/index.js
deleted file mode 100644
index 32858eb08a04f..0000000000000
--- a/packages/react-devtools-shell/src/app/PriorityLevels/index.js
+++ /dev/null
@@ -1,54 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @flow
- */
-
-import * as React from 'react';
-import {Fragment, useCallback, useState} from 'react';
-import {
-  unstable_IdlePriority as IdlePriority,
-  unstable_LowPriority as LowPriority,
-  unstable_runWithPriority as runWithPriority,
-} from 'scheduler';
-
-export default function PriorityLevels() {
-  const [defaultPriority, setDefaultPriority] = useState<boolean>(false);
-  const [idlePriority, setIdlePriority] = useState<boolean>(false);
-  const [normalPriority, setLowPriority] = useState<boolean>(false);
-
-  const resetSequence = useCallback(() => {
-    setDefaultPriority(false);
-    setLowPriority(false);
-    setIdlePriority(false);
-  }, []);
-
-  const startSequence = useCallback(() => {
-    setDefaultPriority(true);
-    runWithPriority(LowPriority, () => setLowPriority(true));
-    runWithPriority(IdlePriority, () => setIdlePriority(true));
-  }, []);
-
-  const labels = [];
-  if (defaultPriority) {
-    labels.push('(default priority)');
-  }
-  if (normalPriority) {
-    labels.push('Low Priority');
-  }
-  if (idlePriority) {
-    labels.push('Idle Priority');
-  }
-
-  return (
-    <Fragment>
-      <h1>Priority Levels</h1>
-      <button onClick={resetSequence}>Reset</button>
-      <button onClick={startSequence}>Start sequence</button>
-      <span>{labels.join(', ')}</span>
-    </Fragment>
-  );
-}
diff --git a/packages/react-devtools-shell/src/app/index.js b/packages/react-devtools-shell/src/app/index.js
index b3c7b9be228c1..f5683b69a82f0 100644
--- a/packages/react-devtools-shell/src/app/index.js
+++ b/packages/react-devtools-shell/src/app/index.js
@@ -15,7 +15,6 @@ import Hydration from './Hydration';
 import InlineWarnings from './InlineWarnings';
 import InspectableElements from './InspectableElements';
 import InteractionTracing from './InteractionTracing';
-import PriorityLevels from './PriorityLevels';
 import ReactNativeWeb from './ReactNativeWeb';
 import ToDoList from './ToDoList';
 import Toggle from './Toggle';
@@ -55,7 +54,6 @@ function mountTestApp() {
   mountHelper(ElementTypes);
   mountHelper(EditableProps);
   mountHelper(InlineWarnings);
-  mountHelper(PriorityLevels);
   mountHelper(ReactNativeWeb);
   mountHelper(Toggle);
   mountHelper(SuspenseTree);