[Merge M100] Fix NPE when dismissing messages on tab destruction

The MessageDispatcher can be null if the activity is being recreated or
destroyed. The other methods in MessageDispatcherBridge null check the
MessageDispatcher before calling any methods, so we should also do this
for dismissMessage(). Note that all messages get dismissed when
detaching the MessageDispatcher from WindowAndroid.

(cherry picked from commit a92ab84)

Bug: 1304262
Change-Id: Idd263ff6d0561b8eb064f73ec06daeb0af427e97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3509779
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#978788}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3514545
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/branch-heads/4896@{#420}
Cr-Branched-From: 1f63ff4-refs/heads/main@{#972766}

components/messages/android/java/src/org/chromium/components/messages/MessageDispatcherBridge.java

@@ -43,6 +43,7 @@ private static boolean enqueueWindowScopedMessage(
     private static void dismissMessage(
             MessageWrapper message, WindowAndroid windowAndroid, @DismissReason int dismissReason) {
         MessageDispatcher messageDispatcher = MessageDispatcherProvider.from(windowAndroid);
+        if (messageDispatcher == null) return;
         messageDispatcher.dismissMessage(message.getMessageProperties(), dismissReason);
     }
 }