[activity] rename unstable_Offscreen to unstable_Activity (#27640)

`Activity` is the current candidate name. This PR starts the rename work
by renaming the exported unstable component name.

NOTE: downstream consumers need to rename the import when updating to
this commit.

Author: kassens

packages/react-dom/src/__tests__/ReactDOMServerPartialHydration-test.internal.js

@@ -10,15 +10,15 @@
 
 'use strict';
 
+let Activity;
 let React = require('react');
 let ReactDOM;
 let ReactDOMClient;
 let ReactDOMServer;
-let Scheduler;
 let ReactFeatureFlags;
+let Scheduler;
 let Suspense;
 let SuspenseList;
-let Offscreen;
 let useSyncExternalStore;
 let act;
 let IdleEventPriority;
@@ -112,8 +112,8 @@ describe('ReactDOMServerPartialHydration', () => {
     act = require('internal-test-utils').act;
     ReactDOMServer = require('react-dom/server');
     Scheduler = require('scheduler');
+    Activity = React.unstable_Activity;
     Suspense = React.Suspense;
-    Offscreen = React.unstable_Offscreen;
     useSyncExternalStore = React.useSyncExternalStore;
     if (gate(flags => flags.enableSuspenseList)) {
       SuspenseList = React.unstable_SuspenseList;
@@ -778,7 +778,7 @@ describe('ReactDOMServerPartialHydration', () => {
     expect(span).not.toBe(span2);
 
     if (gate(flags => flags.dfsEffectsRefactor)) {
-      // The effects list refactor causes this to be null because the Suspense Offscreen's child
+      // The effects list refactor causes this to be null because the Suspense Activity's child
       // is null. However, since we can't hydrate Suspense in legacy this change in behavior is ok
       expect(ref.current).toBe(null);
     } else {
@@ -3151,15 +3151,15 @@ describe('ReactDOMServerPartialHydration', () => {
     expect(ref.current.innerHTML).toBe('Hidden child');
   });
 
-  // @gate enableOffscreen
-  it('a visible Offscreen component acts like a fragment', async () => {
+  // @gate enableActivity
+  it('a visible Activity component acts like a fragment', async () => {
     const ref = React.createRef();
 
     function App() {
       return (
-        <Offscreen mode="visible">
+        <Activity mode="visible">
           <span ref={ref}>Child</span>
-        </Offscreen>
+        </Activity>
       );
     }
 
@@ -3169,7 +3169,7 @@ describe('ReactDOMServerPartialHydration', () => {
     const container = document.createElement('div');
     container.innerHTML = finalHTML;
 
-    // Visible Offscreen boundaries behave exactly like fragments: a
+    // Visible Activity boundaries behave exactly like fragments: a
     // pure indirection.
     expect(container).toMatchInlineSnapshot(`
       <div>
@@ -3187,8 +3187,8 @@ describe('ReactDOMServerPartialHydration', () => {
     expect(ref.current).toBe(span);
   });
 
-  // @gate enableOffscreen
-  it('a hidden Offscreen component is skipped over during server rendering', async () => {
+  // @gate enableActivity
+  it('a hidden Activity component is skipped over during server rendering', async () => {
     const visibleRef = React.createRef();
 
     function HiddenChild() {
@@ -3201,9 +3201,9 @@ describe('ReactDOMServerPartialHydration', () => {
       return (
         <>
           <span ref={visibleRef}>Visible</span>
-          <Offscreen mode="hidden">
+          <Activity mode="hidden">
             <HiddenChild />
-          </Offscreen>
+          </Activity>
         </>
       );
     }

packages/react-reconciler/src/ReactFiber.js

@@ -18,7 +18,7 @@ import type {SuspenseInstance} from './ReactFiberConfig';
 import type {
   OffscreenProps,
   OffscreenInstance,
-} from './ReactFiberOffscreenComponent';
+} from './ReactFiberActivityComponent';
 import type {TracingMarkerInstance} from './ReactFiberTracingMarkerComponent';
 
 import {
@@ -71,7 +71,7 @@ import {
   CacheComponent,
   TracingMarkerComponent,
 } from './ReactWorkTags';
-import {OffscreenVisible} from './ReactFiberOffscreenComponent';
+import {OffscreenVisible} from './ReactFiberActivityComponent';
 import getComponentNameFromFiber from 'react-reconciler/src/getComponentNameFromFiber';
 import {isDevToolsPresent} from './ReactFiberDevToolsHook';
 import {

packages/react-reconciler/src/ReactFiberOffscreenComponent.js renamed to packages/react-reconciler/src/ReactFiberActivityComponent.js

@@ -27,8 +27,8 @@ import type {
   OffscreenState,
   OffscreenQueue,
   OffscreenInstance,
-} from './ReactFiberOffscreenComponent';
-import {OffscreenDetached} from './ReactFiberOffscreenComponent';
+} from './ReactFiberActivityComponent';
+import {OffscreenDetached} from './ReactFiberActivityComponent';
 import type {
   Cache,
   CacheComponentState,

packages/react-reconciler/src/ReactFiberBeginWork.js

@@ -23,13 +23,13 @@ import type {SuspenseState, RetryQueue} from './ReactFiberSuspenseComponent';
 import type {UpdateQueue} from './ReactFiberClassUpdateQueue';
 import type {FunctionComponentUpdateQueue} from './ReactFiberHooks';
 import type {Wakeable} from 'shared/ReactTypes';
-import {isOffscreenManual} from './ReactFiberOffscreenComponent';
+import {isOffscreenManual} from './ReactFiberActivityComponent';
 import type {
   OffscreenState,
   OffscreenInstance,
   OffscreenQueue,
   OffscreenProps,
-} from './ReactFiberOffscreenComponent';
+} from './ReactFiberActivityComponent';
 import type {HookFlags} from './ReactHookEffectTags';
 import type {Cache} from './ReactFiberCacheComponent';
 import type {RootState} from './ReactFiberRoot';
@@ -209,7 +209,7 @@ import {
   OffscreenVisible,
   OffscreenDetached,
   OffscreenPassiveEffectsConnected,
-} from './ReactFiberOffscreenComponent';
+} from './ReactFiberActivityComponent';
 import {
   TransitionRoot,
   TransitionTracingMarker,

packages/react-reconciler/src/ReactFiberCommitWork.js

@@ -24,9 +24,11 @@ import type {
   SuspenseListRenderState,
   RetryQueue,
 } from './ReactFiberSuspenseComponent';
-import type {OffscreenQueue} from './ReactFiberOffscreenComponent';
-import {isOffscreenManual} from './ReactFiberOffscreenComponent';
-import type {OffscreenState} from './ReactFiberOffscreenComponent';
+import type {
+  OffscreenState,
+  OffscreenQueue,
+} from './ReactFiberActivityComponent';
+import {isOffscreenManual} from './ReactFiberActivityComponent';
 import type {TracingMarkerInstance} from './ReactFiberTracingMarkerComponent';
 import type {Cache} from './ReactFiberCacheComponent';
 import {

packages/react-reconciler/src/ReactFiberCompleteWork.js

@@ -17,7 +17,7 @@ import type {
   Update as ClassUpdate,
 } from './ReactFiberClassUpdateQueue';
 import type {Lane, Lanes} from './ReactFiberLane';
-import type {OffscreenInstance} from './ReactFiberOffscreenComponent';
+import type {OffscreenInstance} from './ReactFiberActivityComponent';
 
 import {
   warnAboutUpdateOnNotYetMountedFiberInDEV,
@@ -27,7 +27,7 @@ import {
 import {NoLane, NoLanes, mergeLanes, markHiddenUpdate} from './ReactFiberLane';
 import {NoFlags, Placement, Hydrating} from './ReactFiberFlags';
 import {HostRoot, OffscreenComponent} from './ReactWorkTags';
-import {OffscreenVisible} from './ReactFiberOffscreenComponent';
+import {OffscreenVisible} from './ReactFiberActivityComponent';
 
 export type ConcurrentUpdate = {
   next: ConcurrentUpdate,

packages/react-reconciler/src/ReactFiberConcurrentUpdates.js

@@ -10,7 +10,7 @@
 import type {Fiber} from './ReactInternalTypes';
 import type {StackCursor} from './ReactFiberStack';
 import type {SuspenseProps, SuspenseState} from './ReactFiberSuspenseComponent';
-import type {OffscreenState} from './ReactFiberOffscreenComponent';
+import type {OffscreenState} from './ReactFiberActivityComponent';
 
 import {enableSuspenseAvoidThisFallback} from 'shared/ReactFeatureFlags';
 import {createCursor, push, pop} from './ReactFiberStack';

packages/react-reconciler/src/ReactFiberSuspenseContext.js

@@ -12,7 +12,7 @@ import type {Lane, Lanes} from './ReactFiberLane';
 import type {CapturedValue} from './ReactCapturedValue';
 import type {Update} from './ReactFiberClassUpdateQueue';
 import type {Wakeable} from 'shared/ReactTypes';
-import type {OffscreenQueue} from './ReactFiberOffscreenComponent';
+import type {OffscreenQueue} from './ReactFiberActivityComponent';
 import type {RetryQueue} from './ReactFiberSuspenseComponent';
 
 import getComponentNameFromFiber from 'react-reconciler/src/getComponentNameFromFiber';

packages/react-reconciler/src/ReactFiberThrow.js

@@ -12,7 +12,7 @@ import type {
   Fiber,
   FiberRoot,
 } from './ReactInternalTypes';
-import type {OffscreenInstance} from './ReactFiberOffscreenComponent';
+import type {OffscreenInstance} from './ReactFiberActivityComponent';
 import type {StackCursor} from './ReactFiberStack';
 
 import {enableTransitionTracing} from 'shared/ReactFeatureFlags';

packages/react-reconciler/src/ReactFiberTracingMarkerComponent.js

@@ -21,7 +21,7 @@ import type {
   Transition,
   TransitionAbort,
 } from './ReactFiberTracingMarkerComponent';
-import type {OffscreenInstance} from './ReactFiberOffscreenComponent';
+import type {OffscreenInstance} from './ReactFiberActivityComponent';
 import type {RenderTaskFn} from './ReactFiberRootScheduler';
 
 import {