[ios] Refactor SessionServiceIOS to remove dependency on BrowserState.

ios/chrome/browser/crash_report/crash_restore_helper_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 <Foundation/Foundation.h>
 
 #include <memory>
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 38 matching lines @@
   CrashRestoreHelper* helper_;
 };
 
 TEST_F(CrashRestoreHelperTest, MoveAsideTest) {
   NSString* backupPath = [helper_ sessionBackupPath];
   NSFileManager* fileManager = [NSFileManager defaultManager];
   [fileManager removeItemAtPath:backupPath error:NULL];
 
   NSData* data = [NSData dataWithBytes:"hello" length:5];
   SessionServiceIOS* sessionService = [SessionServiceIOS sharedService];
-  NSString* profileStashPath =
+  NSString* statePath =
       base::SysUTF8ToNSString(chrome_browser_state_->GetStatePath().value());
-  NSString* sessionPath =
-      [sessionService sessionFilePathForDirectory:profileStashPath];
+  NSString* sessionPath = [sessionService sessionPathForDirectory:statePath];
   [fileManager createFileAtPath:sessionPath contents:data attributes:nil];
-  NSString* otrProfileStashPath = base::SysUTF8ToNSString(
+  NSString* otrStatePath = base::SysUTF8ToNSString(

[marq (ping after 24h), 2017/04/11 10:46:29]

Per crbug.com/3333, we prefer to just use 'incognito' instead of 'OTR'. 

(and, if not, we'd prefer offTheRecordStatePath to avoid the initialism).

[sdefresne, 2017/04/11 11:49:41]

Done.

       otr_chrome_browser_state_->GetStatePath().value());
   NSString* otrSessionPath =
-      [sessionService sessionFilePathForDirectory:otrProfileStashPath];
+      [sessionService sessionPathForDirectory:otrStatePath];
   [fileManager createFileAtPath:otrSessionPath contents:data attributes:nil];
 
   [helper_ moveAsideSessionInformation];
 
   EXPECT_EQ(NO, [fileManager fileExistsAtPath:sessionPath]);
   EXPECT_EQ(NO, [fileManager fileExistsAtPath:otrSessionPath]);
   EXPECT_EQ(YES, [fileManager fileExistsAtPath:backupPath]);
   [fileManager removeItemAtPath:backupPath error:NULL];
 }
 
 }  // namespace