Correct iOS build for latest Xcode beta.

ios/web/shell/view_controller.mm

Index: ios/web/shell/view_controller.mm
diff --git a/ios/web/shell/view_controller.mm b/ios/web/shell/view_controller.mm
index 16e78fe72955d84dc38ffc0b678983e3e20f934d..f7c4b93f14b7554f4581f96fe8e40d7cf5afe9a5 100644
--- a/ios/web/shell/view_controller.mm
+++ b/ios/web/shell/view_controller.mm
@@ -10,6 +10,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "ios/net/cookies/cookie_store_ios.h"
 #import "ios/net/crn_http_protocol_handler.h"
+#import "ios/net/empty_nsurlcache.h"
 #import "ios/web/navigation/crw_session_controller.h"
 #include "ios/web/navigation/web_load_params.h"
 #import "ios/web/net/crw_url_verifying_protocol_handler.h"
@@ -130,7 +131,7 @@ bool UseWKWebView() {
 
 - (void)setUpNetworkStack {
   // Disable the default cache.
-  [NSURLCache setSharedURLCache:nil];
+  [NSURLCache setSharedURLCache:[[[EmptyNSURLCache alloc] init] autorelease]];

[shreyasv1, 2015/06/10 15:14:34]

nit: I see that [NSURLCache setSharedURLCache:[[[EmptyNSURLCache alloc] init]
autorelease]];
is being used several times in this CL. Can we move this to a helper function?

[justincohen, 2015/06/10 15:21:11]

I'll defer to droger@ on this one.  I have no clue if this is even correct.  But
it's a fair point.

 
   _httpProtocolDelegate.reset(new web::WebHTTPProtocolHandlerDelegate(
       _browserState->GetRequestContext()));