Removed investigation CHECK from didCommitNavigation.

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 4843 matching lines @@
   }
 
   // This must be reset at the end, since code above may need information about
   // the pending load.
   _pendingNavigationInfo.reset();
   _certVerificationErrors->Clear();
 }
 
 - (void)webView:(WKWebView*)webView
     didCommitNavigation:(WKNavigation*)navigation {
-  // This method will crash if |currentSessionEntry| is null. If this check is
-  // hit it means that |didStartProvisionalNavigation| was called as expected
-  // but it did not call |registerLoadRequest|. TODO(crbug.com/676721): remove
-  // this CHECK once there is at least one crash on this line (which means that
-  // |didStartProvisionalNavigation| did not call |registerLoadRequest| and it
-  // should be fixed.
-  CHECK([self currentSessionEntry] || !navigation ||
-        [_navigationStates stateForNavigation:navigation] ==
-            web::WKNavigationState::STARTED);
-
   [_navigationStates setState:web::WKNavigationState::COMMITTED
                 forNavigation:navigation];
 
   DCHECK_EQ(_webView, webView);
   _certVerificationErrors->Clear();
 
   // This is the point where the document's URL has actually changed, and
   // pending navigation information should be applied to state information.
   [self setDocumentURL:net::GURLWithNSURL([_webView URL])];
 
@@ skipping 568 matching lines @@
   }
 
   return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
 }
 
 - (NSString*)refererFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:@"Referer"];
 }
 
 @end