[ios] Fix uses of ios::ChromeBrowserState in /ios/chrome/browser/ui/signin_interaction

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=jlebel@chromium.org

Bug: 1042208
Change-Id: I567615141ce700cd3edc6327de23b331f38c69a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2017468
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734667}

ios/chrome/browser/ui/signin_interaction/signin_interaction_controller.mm

@@ -113,7 +113,7 @@
     (SigninInteractionControllerCompletionCallback)completion {
   signin_metrics::LogSigninAccessPointStarted(_accessPoint, _promoAction);
   _completionCallback = [completion copy];
-  ios::ChromeBrowserState* browserState = _browser->GetBrowserState();
+  ChromeBrowserState* browserState = _browser->GetBrowserState();
   CoreAccountInfo accountInfo =
       IdentityManagerFactory::GetForBrowserState(browserState)
           ->GetPrimaryAccountInfo();

ios/chrome/browser/ui/signin_interaction/signin_interaction_coordinator.h

@@ -41,8 +41,7 @@ class Browser;
                  dispatcher NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
-                              browserState:
-                                  (ios::ChromeBrowserState*)browserState
+                              browserState:(ChromeBrowserState*)browserState
     NS_UNAVAILABLE;
 
 // Creates a coordinator that uses |viewController| and |browser|.