Gracefully handle didCommitNavigation: call after didFinishNavigation:

ios/web/web_state/ui/crw_wk_navigation_states.mm

 // Copyright 2016 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_wk_navigation_states.h"
 
 #include "base/logging.h"
 #import "ios/web/web_state/navigation_context_impl.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ skipping 104 matching lines @@
   id key = [self keyForNavigation:navigation];
   CRWWKNavigationsStateRecord* record = [_records objectForKey:key];
   if (!record) {
     DCHECK(state == web::WKNavigationState::REQUESTED ||
            state == web::WKNavigationState::STARTED ||
            state == web::WKNavigationState::COMMITTED);
     record =
         [[CRWWKNavigationsStateRecord alloc] initWithState:state
                                                      index:++_lastStateIndex];
   } else {
-    DCHECK(
-        record.state < state ||
-        (record.state == state && state == web::WKNavigationState::REDIRECTED));
+    DCHECK(record.state < state ||
+           // Redirect can be called multiple times.
+           (record.state == state &&
+            state == web::WKNavigationState::REDIRECTED) ||
+           // didFinishNavigation can be called before didCommitNvigation.
+           (record.state == web::WKNavigationState::FINISHED &&
+            state == web::WKNavigationState::COMMITTED));
     record.state = state;
   }
   [_records setObject:record forKey:key];
 }
 
+- (web::WKNavigationState)stateForNavigation:(WKNavigation*)navigation {
+  id key = [self keyForNavigation:navigation];
+  CRWWKNavigationsStateRecord* record = [_records objectForKey:key];
+  return record ? record.state : web::WKNavigationState::NONE;
+}
+
 - (void)removeNavigation:(WKNavigation*)navigation {
   id key = [self keyForNavigation:navigation];
   DCHECK([_records objectForKey:key]);
   [_records removeObjectForKey:key];
 }
 
 - (void)setContext:(std::unique_ptr<web::NavigationContextImpl>)context
      forNavigation:(WKNavigation*)navigation {
   id key = [self keyForNavigation:navigation];
   CRWWKNavigationsStateRecord* record = [_records objectForKey:key];
@@ skipping 56 matching lines @@
     }
   }
 
   if (*outNavigation == _nullNavigation) {
     // |_nullNavigation| is a key for storing null navigations.
     *outNavigation = nil;
   }
 }
 
 @end