Animate the fullscreen exit bubble's opacity instead of its bounds when in immersive fullscreen

chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc

Index: chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc
diff --git a/chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc b/chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc
index ad8e3d3352da3d24a1bac9c50e8aa00937ed23e8..e40ffb59812f14dbff7a4677f63aada2d27b5786 100644
--- a/chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc
+++ b/chrome/browser/ui/fullscreen/fullscreen_exit_bubble.cc
@@ -60,6 +60,10 @@ void FullscreenExitBubble::StopWatchingMouse() {
   mouse_position_checker_.Stop();
 }
 
+bool FullscreenExitBubble::IsWatchingMouse() const {
+  return mouse_position_checker_.IsRunning();
+}
+
 void FullscreenExitBubble::CheckMousePosition() {
   // Desired behavior:
   //
@@ -101,10 +105,12 @@ void FullscreenExitBubble::CheckMousePosition() {
     if (!initial_delay_.IsRunning()) {
       Hide();
     }
-  } else if ((cursor_pos.y() < kSlideInRegionHeightPx) ||
-             IsAnimating()) {
-    // The cursor is not idle, and either it's in the slide-in region or it's in
-    // the neutral region and we're sliding out.
+  } else if (cursor_pos.y() < kSlideInRegionHeightPx &&
+             CanMouseTriggerSlideIn()) {
+    Show();
+  } else if (IsAnimating()) {
+    // The cursor is not idle and either it's in the slide-in region or it's in
+    // the neutral region and we're sliding in or out.
     Show();
   }
 }