Do not create CRWWebUIManager for non-WebUI URLs.

ios/web/web_state/ui/crw_web_controller.h

 // 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.
 
 #ifndef IOS_WEB_WEB_STATE_UI_CRW_WEB_CONTROLLER_H_
 #define IOS_WEB_WEB_STATE_UI_CRW_WEB_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 
 #import "ios/web/net/crw_request_tracker_delegate.h"
@@ skipping 144 matching lines @@
 // Start loading the URL specified in |params|, with the specified
 // settings.  Always resets the openedByScript property to NO.
 // NOTE: |params.transition_type| should never be PAGE_TRANSITION_RELOAD except
 // for transient items, if one needs to reload, call |-reload| explicitly.
 - (void)loadWithParams:(const web::NavigationManager::WebLoadParams&)params;
 
 // Loads the URL indicated by current session state.
 - (void)loadCurrentURL;
 
 // Loads HTML in the page and presents it as if it was originating from an
-// application specific URL.
+// application specific URL. |HTML| must not be empty.
 - (void)loadHTML:(NSString*)HTML forAppSpecificURL:(const GURL&)URL;
 
 // Loads HTML in the page and presents it as if it was originating from the
 // URL itself. Should be used only in specific cases, where the injected html
 // is guaranteed to be some derived representation of the original content.
 - (void)loadHTMLForCurrentURL:(NSString*)HTML;
 
 // Stops loading the page.
 - (void)stopLoading;
 
@@ skipping 95 matching lines @@
 
 // Returns the number of observers registered for this CRWWebController.
 - (NSUInteger)observerCount;
 
 // Loads the HTML into the page at the given URL.
 - (void)loadHTML:(NSString*)HTML forURL:(const GURL&)URL;
 
 @end
 
 #endif  // IOS_WEB_WEB_STATE_UI_CRW_WEB_CONTROLLER_H_