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

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index 7f18cebaf9fa2814eec777f04b0a49647065d55a..ab0b32acd70506771421f602b3a4f202beba78a0 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -590,7 +590,7 @@ - (void)setParentTabModel:(TabModel*)model {
 
 - (NSString*)description {
   return [NSString stringWithFormat:@"%p ... %@ - %s", self, self.title,
-                                    self.url.spec().c_str()];
+                                    self.visibleURL.spec().c_str()];
 }
 
 - (CRWWebController*)webController {
@@ -665,8 +665,8 @@ - (NSString*)originalTitle {
 
 - (NSString*)urlDisplayString {
   base::string16 urlText = url_formatter::FormatUrl(
-      self.url, url_formatter::kFormatUrlOmitNothing, net::UnescapeRule::SPACES,
-      nullptr, nullptr, nullptr);
+      self.visibleURL, url_formatter::kFormatUrlOmitNothing,
+      net::UnescapeRule::SPACES, nullptr, nullptr, nullptr);
   return base::SysUTF16ToNSString(urlText);
 }
 
@@ -694,7 +694,7 @@ - (NSString*)tabId {
 }
 
 - (void)fetchFavicon {
-  const GURL& url = self.url;
+  const GURL& url = self.visibleURL;
   if (!url.is_valid())
     return;
 
@@ -893,7 +893,8 @@ - (void)saveTitleToHistoryDB {
       ios::HistoryServiceFactory::GetForBrowserState(
           browserState_, ServiceAccessType::IMPLICIT_ACCESS);
   DCHECK(historyService);
-  historyService->SetPageTitle(self.url, base::SysNSStringToUTF16(title));
+  historyService->SetPageTitle(self.lastCommittedURL,
+                               base::SysNSStringToUTF16(title));
 }
 
 - (void)addCurrentEntryToHistoryDB {
@@ -1178,7 +1179,7 @@ - (BOOL)openExternalURL:(const GURL&)url
     // Compose u2f-x-callback URL and update urlToOpen.
     finalURL = [U2FController_ XCallbackFromRequestURL:finalURL
                                              originURL:origin
-                                                tabURL:self.url
+                                                tabURL:self.lastCommittedURL
                                                  tabID:self.tabId];
 
     if (!finalURL.is_valid()) {
@@ -1286,19 +1287,21 @@ - (void)handleExportableFile:(net::HttpResponseHeaders*)headers {
     headers->GetNormalizedHeader("content-disposition", &contentDisposition);
   std::string defaultFilename =
       l10n_util::GetStringUTF8(IDS_IOS_OPEN_IN_FILE_DEFAULT_TITLE);
+  const GURL& committedURL = self.lastCommittedURL;
   base::string16 filename =
-      net::GetSuggestedFilename(self.url, contentDisposition,
+      net::GetSuggestedFilename(committedURL, contentDisposition,
                                 "",                 // referrer-charset
                                 "",                 // suggested-name
                                 "application/pdf",  // mime-type
                                 defaultFilename);
   [[self openInController]
-      enableWithDocumentURL:self.url
+      enableWithDocumentURL:committedURL
           suggestedFilename:base::SysUTF16ToNSString(filename)];
 }
 
 - (void)countMainFrameLoad {
-  if ([self isPrerenderTab] || [self url].SchemeIs(kChromeUIScheme)) {
+  if ([self isPrerenderTab] ||
+      self.lastCommittedURL.SchemeIs(kChromeUIScheme)) {
     return;
   }
   base::RecordAction(UserMetricsAction("MobilePageLoaded"));
@@ -1359,7 +1362,7 @@ - (void)loadReaderModeHTML:(NSString*)html forURL:(const GURL&)url {
   // not changed since reader mode was requested. This could happen for example
   // if the page does a late redirect itself or if the user tapped on a link and
   // triggered reader mode before the page load is detected by webState.
-  if (url == self.url)
+  if (url == self.visibleURL)

[Eugene But (OOO till 7-30), 2017/04/14 21:53:47]

This checks that URL did not change, so lastCommittedURL seems to be more
appropriate.

[kkhorimoto, 2017/05/31 22:45:46]

Done.

     [self.webController loadHTMLForCurrentURL:html];
 
   [self.readerModeController exitReaderMode];
@@ -1471,7 +1474,8 @@ - (void)webWillAddPendingURL:(const GURL&)url
   // into a NavigationManager observer callback, so it doesn't need to be
   // checked in several places.
   if (isUserNavigationEvent && !isPrerenderTab_ &&
-      ![self navigationManager]->GetPendingItem() && url != self.url) {
+      ![self navigationManager]->GetPendingItem() &&
+      url != self.lastCommitted) {

[kkhorimoto, 2017/04/14 21:05:16]

If this condition passes the !GetPendingItem() check, then I think we can safely
use the last committed.  Technically, it could have been possible that there was
a transient item, but in practice this never occurs without there also being a
pending item.

[Eugene But (OOO till 7-30), 2017/04/14 21:53:47]

I don't understand this code. Rohit, by any chance do you know what this this
does?

[kkhorimoto, 2017/05/31 22:45:46]

I don't understand super well either, but since the condition has already
calculated that there is no pending item, then the |url| property would always
be returning the last committed URL anyway, so I think we're safe here.

     base::RecordAction(UserMetricsAction("MobileTabClobbered"));
     if ([parentTabModel_ tabUsageRecorder])
       [parentTabModel_ tabUsageRecorder]->RecordPageLoadStart(self);