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

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

 // Copyright 2016 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/session_changes.h"
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_utils.h"
 
-namespace ios_internal {
-
 SessionChanges::SessionChanges(
     std::vector<size_t> const& tabHashesInInitialState,
     std::vector<size_t> const& tabHashesInFinalState) {
-  ios_internal::MinimalReplacementOperations(tabHashesInInitialState,
-                                             tabHashesInFinalState, &updates_,
-                                             &deletions_, &insertions_);
+  TabSwitcherMinimalReplacementOperations(tabHashesInInitialState,
+                                          tabHashesInFinalState, &updates_,
+                                          &deletions_, &insertions_);
 }
 
 SessionChanges::~SessionChanges() {}
 
 std::vector<size_t> const& SessionChanges::deletions() const {
   return deletions_;
 }
 std::vector<size_t> const& SessionChanges::insertions() const {
   return insertions_;
 }
 std::vector<size_t> const& SessionChanges::updates() const {
   return updates_;
 }
 
 bool SessionChanges::hasChanges() const {
   return updates_.size() || deletions_.size() || insertions_.size();
 }
-
-}  // namespace ios_internal