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

ios/chrome/browser/root_coordinator.mm

Index: ios/chrome/browser/root_coordinator.mm
diff --git a/ios/chrome/browser/root_coordinator.mm b/ios/chrome/browser/root_coordinator.mm
index c9f52b6107c804b3288125da88392bc04ea53668..4f7849632961389a18fd3d636f0d98e20189db97 100644
--- a/ios/chrome/browser/root_coordinator.mm
+++ b/ios/chrome/browser/root_coordinator.mm
@@ -4,11 +4,14 @@
 
 #import "ios/chrome/browser/root_coordinator.h"
 
-#include "base/ios/weak_nsobject.h"
 #include "base/logging.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface RootCoordinator () {
-  base::WeakNSObject<UIWindow> _window;
+  __weak UIWindow* _window;

[sdefresne, 2016/12/12 19:37:00]

I think you can synthesize this property.

@synthesize window = _window;

[stkhapugin, 2016/12/13 13:31:11]

Done.

 }
 @end
 
@@ -16,7 +19,7 @@
 
 - (instancetype)initWithWindow:(UIWindow*)window {
   if ((self = [super initWithBaseViewController:nil])) {
-    _window.reset(window);
+    _window = window;
   }
   return self;
 }