[ios] Fix uses of ios::ChromeBrowserState in /ios/chrome/browser/autofill/automation

The ChromeBrowserState has been moved from the "ios" namespace
to the global namespace by http://crrev.com/c/2014913. Fix the
uses from ios::ChromeBrowserState to ChromeBrowserState.

Also remove includes of chrome_browser_state_forward.h and use
a simple forward declaration instead (since the old name is no
longer necessary).

This CL was uploaded by git cl split.

R=mahmadi@chromium.org

Bug: 1042208
Change-Id: I3fdefa9f1f114eaf6e3b07b1d6c474c6bfe403ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2017342Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735265}

ios/chrome/browser/autofill/automation/automation_app_interface.mm

@@ -131,7 +131,7 @@ NSError* PrepareAutofillProfileWithValues(const base::Value* autofill_profile) {
   }
 
   // Save the profile and credit card generated to the personal data manager.
-  ios::ChromeBrowserState* browser_state =
+  ChromeBrowserState* browser_state =
       chrome_test_util::GetOriginalBrowserState();
   PersonalDataManager* personal_data_manager =
       PersonalDataManagerFactory::GetForBrowserState(browser_state);