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

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=marq@chromium.org

Bug: 1042208
Change-Id: I52b9fee727c727d117d7b40c0a17feded176b217
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015173
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735292}

ios/chrome/browser/ui/promos/signin_promo_view_controller.h

@@ -33,7 +33,7 @@ extern NSString* kSigninPromoViewDisplayCountKey;
 @interface SigninPromoViewController : ChromeSigninViewController
 
 // YES if this promo should be shown for |browserState|
-+ (BOOL)shouldBePresentedForBrowserState:(ios::ChromeBrowserState*)browserState;
++ (BOOL)shouldBePresentedForBrowserState:(ChromeBrowserState*)browserState;
 
 // Designated initializer.  |browser| must not be nil.
 - (instancetype)initWithBrowser:(Browser*)browser

ios/chrome/browser/ui/promos/signin_promo_view_controller.mm

@@ -178,8 +178,7 @@ NSSet* GaiaIdSetWithIdentities(NSArray* identities) {
 
 #pragma mark - PromoViewController
 
-+ (BOOL)shouldBePresentedForBrowserState:
-    (ios::ChromeBrowserState*)browserState {
++ (BOOL)shouldBePresentedForBrowserState:(ChromeBrowserState*)browserState {
   if (signin::ForceStartupSigninPromo())
     return YES;
 
@@ -232,7 +231,6 @@ NSSet* GaiaIdSetWithIdentities(NSArray* identities) {
          ![lastKnownGaiaIdSet isEqualToSet:currentGaiaIdSet];
 }
 
-
 #pragma mark - ChromeSigninViewControllerDelegate
 
 - (void)willStartSignIn:(ChromeSigninViewController*)controller {