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

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: I6ac7cb5b57cae580bc39301c21921351869be4ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015174Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735266}

ios/chrome/browser/ui/translate/legacy_translate_infobar_coordinator.h

@@ -20,8 +20,7 @@
 
 // Unavailable, use -initWithBaseViewController:browser:.
 - (instancetype)initWithBaseViewController:(UIViewController*)viewController
-                              browserState:
-                                  (ios::ChromeBrowserState*)browserState
+                              browserState:(ChromeBrowserState*)browserState
     NS_UNAVAILABLE;
 
 @end