[ios] Use chrome_browser_state_forward.h in /ios/chrome/browser/browser_state

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=droger@chromium.org

Bug: 1042208
Change-Id: I62ff45d28f228e1db14f013d511e7a334062272c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2010762
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733327}

ios/chrome/browser/browser_state/bookmark_model_loaded_observer.h

@@ -7,10 +7,7 @@
 
 #include "base/macros.h"
 #include "components/bookmarks/browser/base_bookmark_model_observer.h"
-
-namespace ios {
-class ChromeBrowserState;
-}
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 
 class BookmarkModelLoadedObserver
     : public bookmarks::BaseBookmarkModelObserver {

ios/chrome/browser/browser_state/chrome_browser_state_impl_io_data.h

@@ -9,15 +9,12 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "components/prefs/pref_store.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state_io_data.h"
 #include "ios/chrome/browser/net/net_types.h"
 
 class JsonPrefStore;
 
-namespace ios {
-class ChromeBrowserState;
-}
-
 namespace net {
 class CookieStore;
 class HttpNetworkSession;

ios/chrome/browser/browser_state/chrome_browser_state_io_data.h

@@ -17,6 +17,7 @@
 #include "base/memory/weak_ptr.h"
 #include "components/content_settings/core/common/content_settings_types.h"
 #include "components/prefs/pref_member.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 #include "ios/chrome/browser/ios_chrome_io_thread.h"
 #include "ios/chrome/browser/net/net_types.h"
 #include "net/cert/ct_verifier.h"
@@ -36,11 +37,6 @@ namespace content_settings {
 class CookieSettings;
 }
 
-namespace ios {
-class ChromeBrowserState;
-enum class ChromeBrowserStateType;
-}
-
 namespace net {
 class CookieStore;
 class HttpServerProperties;

ios/chrome/browser/browser_state/chrome_browser_state_manager.h

@@ -9,6 +9,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 
 namespace base {
 class FilePath;
@@ -17,9 +18,6 @@ class FilePath;
 class BrowserStateInfoCache;
 
 namespace ios {
-
-class ChromeBrowserState;
-
 // Provides methods that allow for various ways of creating non-incognito
 // ChromeBrowserState instances. Owns all instances that it creates.
 class ChromeBrowserStateManager {

ios/chrome/browser/browser_state/off_the_record_chrome_browser_state_io_data.h

@@ -11,15 +11,12 @@
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state_io_data.h"
 #include "ios/chrome/browser/net/net_types.h"
 
 class IOSChromeURLRequestContextGetter;
 
-namespace ios {
-class ChromeBrowserState;
-}
-
 namespace net {
 class CookieStore;
 class HttpNetworkSession;