[ios] Use chrome_browser_state_forward.h in /ios/chrome/browser/ui/infobars

Instead of forward declaring ChromeBrowserState in the ios
namespace, use a header. This will allow moving the class
to the global namespace without having to change all the
forward declaration at the same time.

This CL was uploaded by git cl split.

R=sczs@chromium.org

Bug: 1042208
Change-Id: I13fdd8e2da505c318b26b0934a8a73b1bc89e37f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2010840
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734031}

ios/chrome/browser/ui/infobars/coordinators/BUILD.gn

@@ -22,6 +22,7 @@ source_set("coordinators") {
     "//components/infobars/core",
     "//components/translate/core/browser",
     "//ios/chrome/app/strings:ios_strings_grit",
+    "//ios/chrome/browser/browser_state:forward",
     "//ios/chrome/browser/infobars:public",
     "//ios/chrome/browser/infobars:public",
     "//ios/chrome/browser/passwords:infobar_delegates",

ios/chrome/browser/ui/infobars/coordinators/infobar_coordinator.h

@@ -7,6 +7,7 @@
 
 #import "ios/chrome/browser/ui/coordinators/chrome_coordinator.h"
 
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 #import "ios/chrome/browser/infobars/infobar_type.h"
 #import "ios/chrome/browser/ui/infobars/banners/infobar_banner_delegate.h"
 #import "ios/chrome/browser/ui/infobars/infobar_ui_delegate.h"
@@ -21,9 +22,6 @@
 @class InfobarModalTransitionDriver;
 @class InfobarModalViewController;
 
-namespace ios {
-class ChromeBrowserState;
-}
 namespace infobars {
 class InfoBarDelegate;
 }