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

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=pkl@chromium.org

Bug: 1042208
Change-Id: I071f9a83d5ed93208d2271c405ee153f46aa8920
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015059Reviewed-by: Peter Lee <pkl@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735278}

ios/chrome/browser/app_launcher/app_launcher_tab_helper.mm

@@ -218,8 +218,8 @@ bool AppLauncherTabHelper::ShouldAllowRequest(
   bool is_link_transition = ui::PageTransitionTypeIncludingQualifiersIs(
       request_info.transition_type, ui::PAGE_TRANSITION_LINK);
 
-  ios::ChromeBrowserState* browser_state =
-      ios::ChromeBrowserState::FromBrowserState(web_state_->GetBrowserState());
+  ChromeBrowserState* browser_state =
+      ChromeBrowserState::FromBrowserState(web_state_->GetBrowserState());
 
   if (!is_link_transition && original_pending_url.is_valid()) {
     // At this stage the navigation will be canceled in all cases. If this

ios/chrome/browser/app_launcher/app_launcher_tab_helper_unittest.mm

@@ -94,8 +94,8 @@ class FakeNavigationManager : public web::TestNavigationManager {
 
 std::unique_ptr<KeyedService> BuildReadingListModel(
     web::BrowserState* context) {
-  ios::ChromeBrowserState* browser_state =
-      ios::ChromeBrowserState::FromBrowserState(context);
+  ChromeBrowserState* browser_state =
+      ChromeBrowserState::FromBrowserState(context);
   std::unique_ptr<ReadingListModelImpl> reading_list_model(
       new ReadingListModelImpl(nullptr, browser_state->GetPrefs(),
                                base::DefaultClock::GetInstance()));