[ios] Moves tab_switcher code out of the ios_internal namespace.

ios/chrome/browser/ui/tab_switcher/tab_switcher_panel_view.h

 // Copyright 2015 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.
 
 #ifndef IOS_CHROME_BROWSER_UI_TAB_SWITCHER_TAB_SWITCHER_PANEL_VIEW_H_
 #define IOS_CHROME_BROWSER_UI_TAB_SWITCHER_TAB_SWITCHER_PANEL_VIEW_H_
 
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_model.h"
 
 @class TabSwitcherCache;
 
 @interface TabSwitcherPanelView : UIView
 
 @property(nonatomic, readonly) UICollectionView* collectionView;
 
-- (instancetype)initWithSessionType:(ios_internal::SessionType)sessionType
+- (instancetype)initWithSessionType:(SessionType)sessionType
     NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithFrame:(CGRect)frame NS_UNAVAILABLE;
 - (instancetype)initWithCoder:(NSCoder*)aDecoder NS_UNAVAILABLE;
 
 // Updates the collectionView's layout to ensure that the optimal amount of tabs
 // are displayed. The completion block is called at the end of the layout
 // update.
 - (void)updateCollectionLayoutWithCompletion:(void (^)(void))completion;
 
 // Returns the size of the cells displayed in the collectionView.
 - (CGSize)cellSize;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_TAB_SWITCHER_TAB_SWITCHER_PANEL_VIEW_H_