[ObjC ARC] Converts ios/chrome/browser/metrics:metrics_internal to ARC.

ios/chrome/browser/metrics/size_class_recorder.mm

Index: ios/chrome/browser/metrics/size_class_recorder.mm
diff --git a/ios/chrome/browser/metrics/size_class_recorder.mm b/ios/chrome/browser/metrics/size_class_recorder.mm
index 8e90ebe385272e53240142efafd4ce3392d0a1bc..fa94ae269bbf0e93881f4c3ba9c177236c8f6dad 100644
--- a/ios/chrome/browser/metrics/size_class_recorder.mm
+++ b/ios/chrome/browser/metrics/size_class_recorder.mm
@@ -9,6 +9,10 @@
 #include "base/metrics/histogram_macros.h"
 #import "ios/chrome/browser/ui/ui_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace ios_internal {
 
 // Converts a UIKit size class to a size class for reporting.
@@ -89,7 +93,6 @@ void ReportHorizontalSizeClassUsed(UIUserInterfaceSizeClass sizeClass) {
 
 - (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
-  [super dealloc];
 }
 
 - (void)horizontalSizeClassDidChange:(UIUserInterfaceSizeClass)newSizeClass {