[ios Mojo] Enabled Mojo WebUI by default.

ios/web/web_state/ui/crw_web_controller.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 996 matching lines @@
 const NSTimeInterval kSnapshotOverlayTransition = 0.5;
 
 }  // namespace
 
 @implementation CRWWebController
 
 @synthesize webUsageEnabled = _webUsageEnabled;
 @synthesize usePlaceholderOverlay = _usePlaceholderOverlay;
 @synthesize loadPhase = _loadPhase;
 @synthesize shouldSuppressDialogs = _shouldSuppressDialogs;
-@synthesize useMojoForWebUI = _useMojoForWebUI;
 
 - (instancetype)initWithWebState:(WebStateImpl*)webState {
   self = [super init];
   if (self) {
     _webStateImpl = webState;
     DCHECK(_webStateImpl);
     _webStateImpl->InitializeRequestTracker(self);
     // Load phase when no WebView present is 'loaded' because this represents
     // the idle state.
     _loadPhase = web::PAGE_LOADED;
@@ skipping 3845 matching lines @@
   }
 }
 
 - (void)webView:(WKWebView*)webView
     runJavaScriptTextInputPanelWithPrompt:(NSString*)prompt
                               defaultText:(NSString*)defaultText
                          initiatedByFrame:(WKFrameInfo*)frame
                         completionHandler:
                             (void (^)(NSString* result))completionHandler {
   GURL origin(web::GURLOriginWithWKSecurityOrigin(frame.securityOrigin));
-  if (self.useMojoForWebUI && web::GetWebClient()->IsAppSpecificURL(origin) &&
-      _webUIManager) {
+  if (web::GetWebClient()->IsAppSpecificURL(origin) && _webUIManager) {
     std::string mojoResponse =
         self.mojoFacade->HandleMojoMessage(base::SysNSStringToUTF8(prompt));
     completionHandler(base::SysUTF8ToNSString(mojoResponse));
     return;
   }
 
   if (self.shouldSuppressDialogs) {
     [self didSuppressDialog];
     completionHandler(nil);
     return;
@@ skipping 692 matching lines @@
   }
 
   return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
 }
 
 - (NSString*)refererFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:@"Referer"];
 }
 
 @end