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

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=eugenebut@chromium.org

Bug: 1042208
Change-Id: Ie802b1bbdc036ff2089a5874286a2b62fdbb4fb8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2014919
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735295}

ios/chrome/browser/ui/download/ar_quick_look_coordinator.h

@@ -32,8 +32,7 @@ enum class PresentQLPreviewController {
 
 // Unavailable, use -initWithBaseViewController:browser:
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
-                              browserState:
-                                  (ios::ChromeBrowserState*)browserState
+                              browserState:(ChromeBrowserState*)browserState
     NS_UNAVAILABLE;
 
 @end

ios/chrome/browser/ui/download/pass_kit_coordinator.h

@@ -50,8 +50,7 @@ enum class PresentAddPassesDialogResult {
 
 // Use -initWithBaseViewController:browser:
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
-                              browserState:
-                                  (ios::ChromeBrowserState*)browserState
+                              browserState:(ChromeBrowserState*)browserState
     NS_UNAVAILABLE;
 
 // Must be set before calling |start| method. Set to null when stop method is