Remove usage of Tab's |url| property from TabModel.

ios/chrome/browser/tabs/tab_model.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/chrome/browser/tabs/tab_model.h"
 
 #include <cstdint>
 #include <utility>
 #include <vector>
 
@@ skipping 575 matching lines @@
   if (_tabUsageRecorder)
     _tabUsageRecorder->RecordPrimaryTabModelChange(primary, self.currentTab);
 }
 
 - (NSSet*)currentlyReferencedExternalFiles {
   NSMutableSet* referencedFiles = [NSMutableSet set];
   if (!_browserState)
     return referencedFiles;
   // Check the currently open tabs for external files.
   for (Tab* tab in self) {
-    if (UrlIsExternalFileReference(tab.url)) {
-      NSString* fileName = base::SysUTF8ToNSString(tab.url.ExtractFileName());
+    const GURL& lastCommittedURL = tab.lastCommittedURL;
+    web::NavigationItem* pendingItem =
+        tab.webState->GetNavigationManager()->GetPendingItem();
+    const GURL& pendingURL =
+        pendingItem ? pendingItem->GetURL() : GURL::EmptyGURL();
+    if (UrlIsExternalFileReference(lastCommittedURL) ||
+        UrlIsExternalFileReference(pendingURL)) {
+      NSString* fileName = base::SysUTF8ToNSString(URL.ExtractFileName());

[Eugene But (OOO till 7-30), 2017/05/31 22:43:11]

Does it compile? I can't fine |URL| variable.

[kkhorimoto, 2017/06/01 17:55:33]

Whoop, I think I accidentally reverted or something when trying to upload this. 
I uploaded an actual fix.

       [referencedFiles addObject:fileName];
     }
   }
   // Do the same for the recently closed tabs.
   sessions::TabRestoreService* restoreService =
       IOSChromeTabRestoreServiceFactory::GetForBrowserState(_browserState);
   DCHECK(restoreService);
   for (const auto& entry : restoreService->entries()) {
     sessions::TabRestoreService::Tab* tab =
         static_cast<sessions::TabRestoreService::Tab*>(entry.get());
@@ skipping 133 matching lines @@
     // Restore the CertificatePolicyCache (note that webState is invalid after
     // passing it via move semantic to -initWithWebState:model:).
     UpdateCertificatePolicyCacheFromWebState(policyCache, [tab webState]);
     [restoredTabs addObject:tab];
   }
 
   // If there was only one tab and it was the new tab page, clobber it.
   BOOL closedNTPTab = NO;
   if (oldCount == 1) {
     Tab* tab = [self tabAtIndex:0];
-    if (tab.url == GURL(kChromeUINewTabURL)) {
+    BOOL hasPendingLoad =
+        tab.webState->GetNavigationManager()->GetPendingItem() != nullptr;
+    if (!hasPendingLoad && tab.lastCommittedURL == GURL(kChromeUINewTabURL)) {
       [self closeTab:tab];
       closedNTPTab = YES;
       oldCount = 0;
     }
   }
   if (_tabUsageRecorder)
     _tabUsageRecorder->InitialRestoredTabs(self.currentTab, restoredTabs);
   return closedNTPTab;
 }
 
@@ skipping 35 matching lines @@
 }
 
 // Called when UIApplicationWillEnterForegroundNotification is received.
 - (void)applicationWillEnterForeground:(NSNotification*)notify {
   if (_tabUsageRecorder) {
     _tabUsageRecorder->AppWillEnterForeground();
   }
 }
 
 @end