Don't re-use a zoom bubble unless it has the same web-contents.

chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc

Index: chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc
diff --git a/chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc b/chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc
index a8068ba79351d41211ff8484834ace87538052f4..e76c8cc737ee329a10497e20ab6df43f7164c033 100644
--- a/chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc
+++ b/chrome/browser/ui/views/location_bar/zoom_bubble_view_browsertest.cc
@@ -95,7 +95,7 @@ IN_PROC_BROWSER_TEST_F(ZoomBubbleBrowserTest, ImmersiveFullscreen) {
       immersive_controller->GetRevealedLock(
           ImmersiveModeController::ANIMATE_REVEAL_NO));
   ASSERT_TRUE(immersive_controller->IsRevealed());
-  EXPECT_TRUE(ZoomBubbleView::zoom_bubble_->GetWidget()->IsClosed());
+  EXPECT_EQ(NULL, ZoomBubbleView::zoom_bubble_);
 
   // The zoom bubble should be anchored when it is shown in immersive fullscreen
   // and the top-of-window views are revealed.