Renames SessionChanges and SessionCellData to have a TabSwitcher prefix.

ios/chrome/browser/ui/tab_switcher/tab_switcher_header_cell.mm

 // 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.
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_header_cell.h"
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_session_cell_data.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
@@ skipping 25 matching lines @@
 }
 
 + (NSString*)identifier {
   return @"TabSwitcherHeaderCell";
 }
 
 - (NSString*)reuseIdentifier {
   return [[self class] identifier];
 }
 
-- (void)loadSessionCellData:(SessionCellData*)sessionCellData {
+- (void)loadSessionCellData:(TabSwitcherSessionCellData*)sessionCellData {
   [_imageView setImage:sessionCellData.image];
   [_label setText:sessionCellData.title];
   [self setNeedsLayout];
 }
 
 - (void)setSelected:(BOOL)selected {
   [super setSelected:selected];
   [_imageView setAlpha:selected ? 1. : kInactiveAlpha];
   [_label setAlpha:selected ? 1. : kInactiveAlpha];
   [self setNeedsLayout];
@@ skipping 23 matching lines @@
   [stackView setTranslatesAutoresizingMaskIntoConstraints:NO];
   [NSLayoutConstraint activateConstraints:@[
     [self.contentView.centerYAnchor
         constraintEqualToAnchor:[stackView centerYAnchor]],
     [self.contentView.centerXAnchor
         constraintEqualToAnchor:[stackView centerXAnchor]]
   ]];
 }
 
 @end