[ios] Cleanup SessionServiceIOS implementation.

ios/chrome/browser/sessions/session_window_ios_unittest.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/sessions/session_window_ios.h"
 
 #import <Foundation/Foundation.h>
 
 #import "ios/web/public/crw_session_storage.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 28 matching lines @@
   EXPECT_EQ(static_cast<NSUInteger>(NSNotFound), session_window.selectedIndex);
 }
 
 TEST_F(SessionWindowIOSTest, InitWithSessions) {
   SessionWindowIOS* session_window = CreateSessionWindowForTest(0u);
 
   EXPECT_EQ(2u, [session_window.sessions count]);
   EXPECT_EQ(0u, session_window.selectedIndex);
 }
 
-TEST_F(SessionWindowIOSTest, ClearSessions) {
-  SessionWindowIOS* session_window = CreateSessionWindowForTest(0u);
-
-  ASSERT_EQ(2u, [session_window.sessions count]);
-  ASSERT_EQ(0u, session_window.selectedIndex);
-
-  [session_window clearSessions];
-  EXPECT_EQ(0u, [session_window.sessions count]);
-  EXPECT_EQ(static_cast<NSUInteger>(NSNotFound), session_window.selectedIndex);
-}
-
 TEST_F(SessionWindowIOSTest, CodingEncoding) {
   SessionWindowIOS* original_session_window = CreateSessionWindowForTest(1u);
 
   NSData* data =
       [NSKeyedArchiver archivedDataWithRootObject:original_session_window];
   ASSERT_TRUE(data != nil);
 
   SessionWindowIOS* unarchived_session_window =
       [NSKeyedUnarchiver unarchiveObjectWithData:data];
   ASSERT_TRUE(unarchived_session_window != nil);
 
   EXPECT_EQ(1u, unarchived_session_window.selectedIndex);
   ASSERT_EQ(2u, [unarchived_session_window.sessions count]);
 
   EXPECT_TRUE(unarchived_session_window.sessions[0].hasOpener);
   EXPECT_FALSE(unarchived_session_window.sessions[1].hasOpener);
 }