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

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=erikchen@chromium.org

Bug: 1042208
Change-Id: I0ad3931c7241d5ab243a7dfcc5a54c8258dd08e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2017350Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735282}

ios/chrome/browser/device_sharing/device_sharing_manager.h

@@ -7,8 +7,7 @@
 
 #import <Foundation/Foundation.h>
 
-#include "ios/chrome/browser/browser_state/chrome_browser_state_forward.h"
-
+class ChromeBrowserState;
 class GURL;
 @class HandoffManager;
 
@@ -27,7 +26,7 @@ class GURL;
 // |-updateBrowserState:nullptr| before |browserState| is destroyed.
 //
 // |browserState| must not be off the record.
-- (void)updateBrowserState:(ios::ChromeBrowserState*)browserState;
+- (void)updateBrowserState:(ChromeBrowserState*)browserState;
 
 // Updates the active URL to be shared with other devices. This method is
 // a no-op if the active browser state was never set previously.

ios/chrome/browser/device_sharing/device_sharing_manager.mm

@@ -19,7 +19,7 @@
 #endif
 
 @interface DeviceSharingManager ()<PrefObserverDelegate> {
-  ios::ChromeBrowserState* _browserState;  // weak
+  ChromeBrowserState* _browserState;  // weak
 
   // Bridge to listen to pref changes to the active browser state.
   std::unique_ptr<PrefObserverBridge> _browserStatePrefObserverBridge;
@@ -43,7 +43,7 @@
 
 @implementation DeviceSharingManager
 
-- (void)updateBrowserState:(ios::ChromeBrowserState*)state {
+- (void)updateBrowserState:(ChromeBrowserState*)state {
   DCHECK(!state || !state->IsOffTheRecord());
   if (_browserState == state) {
     return;