[ios] Refactor SessionServiceIOS to remove dependency on BrowserState.

ios/chrome/browser/ui/main/browser_view_wrangler.mm

Index: ios/chrome/browser/ui/main/browser_view_wrangler.mm
diff --git a/ios/chrome/browser/ui/main/browser_view_wrangler.mm b/ios/chrome/browser/ui/main/browser_view_wrangler.mm
index c68d876c48a067bd74454bbf6ba8a0107c8581ae..ff14281cd2cf6d90738bea774dd47c9c8c85291a 100644
--- a/ios/chrome/browser/ui/main/browser_view_wrangler.mm
+++ b/ios/chrome/browser/ui/main/browser_view_wrangler.mm
@@ -6,6 +6,7 @@
 
 #include "base/mac/objc_property_releaser.h"
 #import "base/mac/scoped_nsobject.h"
+#include "base/strings/sys_string_conversions.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #import "ios/chrome/browser/browsing_data/browsing_data_removal_controller.h"
@@ -297,8 +298,11 @@
   SessionWindowIOS* sessionWindow = nil;
   if (!empty) {
     // Load existing saved tab model state.
-    sessionWindow = [[SessionServiceIOS sharedService]
-        loadWindowForBrowserState:browserState];
+    SessionServiceIOS* sessionService = [SessionServiceIOS sharedService];
+    NSString* statePath =
+        base::SysUTF8ToNSString(browserState->GetStatePath().AsUTF8Unsafe());
+    NSString* sessionPath = [sessionService sessionPathForDirectory:statePath];
+    sessionWindow = [sessionService loadSessionWindowFromPath:sessionPath];
   }
 
   // Create tab model from saved session (nil is ok).