Add mechanism to get the Tab from the associated WebState.

ios/chrome/browser/tabs/tab.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.h"
 
 #import <CoreLocation/CoreLocation.h>
 #import <UIKit/UIKit.h>
 
 #include <utility>
@@ skipping 70 matching lines @@
 #include "ios/chrome/browser/signin/account_reconcilor_factory.h"
 #include "ios/chrome/browser/signin/authentication_service.h"
 #include "ios/chrome/browser/signin/authentication_service_factory.h"
 #include "ios/chrome/browser/signin/signin_capability.h"
 #import "ios/chrome/browser/snapshots/snapshot_manager.h"
 #import "ios/chrome/browser/snapshots/snapshot_overlay_provider.h"
 #import "ios/chrome/browser/snapshots/web_controller_snapshot_helper.h"
 #include "ios/chrome/browser/ssl/ios_security_state_tab_helper.h"
 #import "ios/chrome/browser/storekit_launcher.h"
 #include "ios/chrome/browser/sync/ios_chrome_synced_tab_delegate.h"
+#import "ios/chrome/browser/tabs/legacy_tab_helper.h"
 #import "ios/chrome/browser/tabs/tab_delegate.h"
 #import "ios/chrome/browser/tabs/tab_dialog_delegate.h"
 #import "ios/chrome/browser/tabs/tab_headers_delegate.h"
 #import "ios/chrome/browser/tabs/tab_model.h"
 #import "ios/chrome/browser/tabs/tab_private.h"
 #import "ios/chrome/browser/tabs/tab_snapshotting_delegate.h"
 #include "ios/chrome/browser/translate/chrome_ios_translate_client.h"
 #import "ios/chrome/browser/u2f/u2f_controller.h"
 #import "ios/chrome/browser/ui/commands/UIKit+ChromeExecuteCommand.h"
 #import "ios/chrome/browser/ui/commands/generic_chrome_command.h"
@@ skipping 427 matching lines @@
     propertyReleaser_Tab_.Init(self, [Tab class]);
     tabHistoryContext_.reset(new TabHistoryContext());
     parentTabModel_ = parentModel;
     browserState_ =
         ios::ChromeBrowserState::FromBrowserState(webState->GetBrowserState());
 
     webStateImpl_.reset(static_cast<web::WebStateImpl*>(webState.release()));
     webStateObserver_.reset(
         new web::WebStateObserverBridge(webStateImpl_.get(), self));
 
+    // Do not respect |attachTabHelpers| as this tab helper is required for
+    // proper conversion from WebState to Tab.
+    LegacyTabHelper::CreateForWebState(webStateImpl_.get(), self);
+
     [self.webController setDelegate:self];
 
     NSString* sessionID = self.tabId;
     DCHECK(sessionID);
     snapshotManager_.reset([[SnapshotManager alloc] init]);
 
     webControllerSnapshotHelper_.reset([[WebControllerSnapshotHelper alloc]
         initWithSnapshotManager:snapshotManager_
                             tab:self]);
 
@@ skipping 693 matching lines @@
   // CRWWebController to be deallocated before its close is called.  The facade
   // delegate should be torn down after |-didCloseTab:| so components triggered
   // by tab closure can use the content facade, and it should be deleted before
   // the web controller since the web controller owns the facade's backing
   // objects.
   // TODO(crbug.com/546222): Fix the need for this; TabModel should be
   // responsible for making the lifetime of Tab sane, rather than allowing Tab
   // to drive its own destruction.
   base::scoped_nsobject<Tab> kungFuDeathGrip([self retain]);
   [parentTabModel_ didCloseTab:self];  // Inform parent of tab closure.
+
+  LegacyTabHelper::RemoveFromWebState(webStateImpl_.get());

[rohitrao (ping after 24h), 2017/02/08 14:07:17]

Is there any way for code to call LegacyTabHelper::FromWebState() after this
line is run?  I don't want to require null-checking.  If it's basically
impossible for code to run after this call, then that's ok.  (Otherwise we
should consider calling SetTab(nil) instead of removing the helper completely.)

[sdefresne, 2017/02/08 14:45:34]

I've addressed this by introducing a static method
LegacyTabHelper::GetTabForWebState() that does the null check.

   webStateImpl_.reset();
 }
 
 - (void)dismissModals {
   [openInController_ disable];
   [self.webController dismissModals];
 }
 
 - (CRWSessionEntry*)currentSessionEntry {
   if (![self navigationManager])
@@ skipping 987 matching lines @@
 
 - (TabModel*)parentTabModel {
   return parentTabModel_;
 }
 
 - (FormInputAccessoryViewController*)inputAccessoryViewController {
   return inputAccessoryViewController_.get();
 }
 
 @end