BottomSheet: Fix bottom sheet being hidden due to suppression

A bug causing FullscreenManager to call #onEnterFullscreen
more often than #onExitFullscreen makes BottomSheet suppressed.
This CL makes sure BottomSheetManager handle suppress token
in such a way that the number of the same event calls doesn't
matter.

Bug: 1157368
Change-Id: I70b951dffc242d8da75fa74bc451a5d0864536d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2589143
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836938}

chrome/android/java/src/org/chromium/chrome/browser/ui/BottomSheetManager.java

@@ -241,7 +241,9 @@ class BottomSheetManager extends EmptyBottomSheetObserver implements Destroyable
                 }
 
                 if (mTabProvider.get() != tab) return;
+                int previousToken = mToken;
                 mToken = controller.suppressSheet(StateChangeReason.COMPOSITED_UI);
+                controller.unsuppressSheet(previousToken);
             }
 
             @Override