Use 'pagehide' for page termination by default.

.changeset/perfect-comics-march.md

@@ -0,0 +1,5 @@
+---
+"@firebase/firestore": patch
+---
+
+Use 'pagehide' for page termination by default.

packages/firestore/src/local/indexeddb_persistence.ts

@@ -966,7 +966,7 @@ export class IndexedDbPersistence implements Persistence {
           return this.shutdown();
         });
       };
-      this.window.addEventListener('unload', this.windowUnloadHandler);
+      this.window.addEventListener('pagehide', this.windowUnloadHandler);
     }
   }
 
@@ -976,7 +976,7 @@ export class IndexedDbPersistence implements Persistence {
         typeof this.window?.removeEventListener === 'function',
         "Expected 'window.removeEventListener' to be a function"
       );
-      this.window!.removeEventListener('unload', this.windowUnloadHandler);
+      this.window!.removeEventListener('pagehide', this.windowUnloadHandler);
       this.windowUnloadHandler = null;
     }
   }

packages/firestore/src/local/shared_client_state.ts

@@ -613,7 +613,7 @@ export class WebStorageSharedClientState implements SharedClientState {
 
     // Register a window unload hook to remove the client metadata entry from
     // WebStorage even if `shutdown()` was not called.
-    this.window.addEventListener('unload', () => this.shutdown());
+    this.window.addEventListener('pagehide', () => this.shutdown());
 
     this.started = true;
   }

packages/firestore/test/util/test_platform.ts

@@ -58,7 +58,7 @@ export class FakeWindow implements WindowLike {
       case 'storage':
         this.storageListeners.push(listener);
         break;
-      case 'unload':
+      case 'pagehide':
       case 'visibilitychange':
         // The spec tests currently do not rely on `unload`/`visibilitychange`
         // listeners.