[ARC] Converts parts of ios/web/web_state to ARC.

ios/web/web_state/crw_web_view_proxy_impl.mm

Index: ios/web/web_state/crw_web_view_proxy_impl.mm
diff --git a/ios/web/web_state/crw_web_view_proxy_impl.mm b/ios/web/web_state/crw_web_view_proxy_impl.mm
index 73c6b03459b8ddf7c1a3ae81e66cd40eb7c6ea91..9996420585aa46fa6f314cf02734cd33e42b5f16 100644
--- a/ios/web/web_state/crw_web_view_proxy_impl.mm
+++ b/ios/web/web_state/crw_web_view_proxy_impl.mm
@@ -5,12 +5,15 @@
 #import "ios/web/web_state/crw_web_view_proxy_impl.h"
 
 #include "base/ios/ios_util.h"
-#include "base/ios/weak_nsobject.h"
 #include "base/mac/scoped_nsobject.h"
 #import "ios/web/public/web_state/crw_web_view_scroll_view_proxy.h"
 #import "ios/web/public/web_state/ui/crw_content_view.h"
 #import "ios/web/web_state/ui/crw_web_controller.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // Returns the first responder in the subviews of |view|, or nil if no view in
@@ -66,20 +69,20 @@ UIView* GetFirstResponderSubview(UIView* view) {
 @end
 
 @implementation CRWWebViewProxyImpl {
-  base::WeakNSObject<CRWContentView> _contentView;
-  base::WeakNSObject<CRWWebController> _webController;
+  __weak CRWWebController* _webController;
   base::scoped_nsobject<NSMutableDictionary> _registeredInsets;
   // The WebViewScrollViewProxy is a wrapper around the web view's
   // UIScrollView to give components access in a limited and controlled manner.
   base::scoped_nsobject<CRWWebViewScrollViewProxy> _contentViewScrollViewProxy;
 }
+@synthesize contentView = _contentView;
 
 - (instancetype)initWithWebController:(CRWWebController*)webController {
   self = [super init];
   if (self) {
     DCHECK(webController);
     _registeredInsets.reset([[NSMutableDictionary alloc] init]);
-    _webController.reset(webController);
+    _webController = webController;
     _contentViewScrollViewProxy.reset([[CRWWebViewScrollViewProxy alloc] init]);
   }
   return self;
@@ -146,12 +149,8 @@ UIView* GetFirstResponderSubview(UIView* view) {
   [_registeredInsets removeObjectForKey:callerValue];
 }
 
-- (CRWContentView*)contentView {
-  return _contentView.get();
-}
-
 - (void)setContentView:(CRWContentView*)contentView {
-  _contentView.reset(contentView);
+  _contentView = contentView;
   [_contentViewScrollViewProxy setScrollView:contentView.scrollView];
 }