[ObjC ARC] Converts ios/chrome/browser/ui:ui_internal to ARC.

ios/chrome/browser/ui/fullscreen_controller.mm

Index: ios/chrome/browser/ui/fullscreen_controller.mm
diff --git a/ios/chrome/browser/ui/fullscreen_controller.mm b/ios/chrome/browser/ui/fullscreen_controller.mm
index ed7ac0ea475c38540f4c9e09a2d20e106f0f8743..8789d625c7d0bce0d8b06dee8c31b7376e469eb3 100644
--- a/ios/chrome/browser/ui/fullscreen_controller.mm
+++ b/ios/chrome/browser/ui/fullscreen_controller.mm
@@ -75,8 +75,7 @@ BOOL CGFloatEquals(CGFloat a, CGFloat b) {
 }
 
 // Access to the UIWebView's UIScrollView.
-@property(unsafe_unretained, nonatomic, readonly)
-    CRWWebViewScrollViewProxy* scrollViewProxy;
+@property(weak, nonatomic, readonly) CRWWebViewScrollViewProxy* scrollViewProxy;
 // The navigation controller of the page.
 @property(nonatomic, readonly, assign) NavigationManager* navigationManager;
 // The gesture recognizer set on the scrollview to detect tap. Must be readwrite
@@ -85,9 +84,7 @@ BOOL CGFloatEquals(CGFloat a, CGFloat b) {
     UITapGestureRecognizer* userInteractionGestureRecognizer;
 // The delegate responsible for providing the header height and moving the
 // header.
-@property(unsafe_unretained, nonatomic, readonly)
-    id<FullScreenControllerDelegate>
-        delegate;
+@property(weak, nonatomic, readonly) id<FullScreenControllerDelegate> delegate;
 // Current height of the header, in points. This is a pass-through method that
 // fetches the header height from the FullScreenControllerDelegate.
 @property(nonatomic, readonly) CGFloat headerHeight;