Reland "Extract unified consent constants target."

This is a reland of cf629e19

Added import of constants.h file in unified_consent_view_controller.h so that
internal egtests can continue access the constants. After this CL lands, will
change the egtest header in internal code base and remove the constants.h
header import here.

Original change's description:
> Extract unified consent constants target.
>
> Preparing for SigninEarlGreyUI and SigninEarlGreyUtils EG2 migrations.
>
> Bug: 922813, 1015907
> Change-Id: I47e4678e40f1820b22938463c5a791c04a662f3c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1884286
> Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
> Reviewed-by: Rohit Rao <rohitrao@chromium.org>
> Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#710479}

Bug: 922813, 1015907
Change-Id: I4584bfdda1a4854e17aac174ba1906b9e80adf09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1888601
Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710614}

ios/chrome/browser/ui/authentication/chrome_signin_view_controller_unittest.mm

@@ -22,6 +22,7 @@
 #include "ios/chrome/browser/signin/identity_manager_factory.h"
 #include "ios/chrome/browser/sync/consent_auditor_factory.h"
 #include "ios/chrome/browser/sync/ios_user_event_service_factory.h"
+#import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_view_controller.h"
 #import "ios/chrome/browser/ui/util/transparent_link_button.h"
 #include "ios/chrome/browser/unified_consent/unified_consent_service_factory.h"

ios/chrome/browser/ui/authentication/signin_earl_grey_ui.mm

@@ -11,6 +11,7 @@
 #import "ios/chrome/browser/ui/authentication/signin_earlgrey_utils.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/identity_chooser/identity_chooser_cell.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/identity_picker_view.h"
+#import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_view_controller.h"
 #import "ios/chrome/browser/ui/signin_interaction/signin_interaction_controller_egtest_util.h"
 #import "ios/chrome/browser/ui/util/transparent_link_button.h"

ios/chrome/browser/ui/authentication/unified_consent/BUILD.gn

@@ -48,4 +48,16 @@ source_set("unified_consent_ui") {
     "//ios/third_party/material_components_ios",
     "//ui/base",
   ]
+  public_deps = [
+    ":constants",
+  ]
+}
+
+source_set("constants") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  sources = [
+    "unified_consent_constants.h",
+    "unified_consent_constants.mm",
+  ]
+  libs = [ "Foundation.framework" ]
 }

ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_CHROME_BROWSER_UI_AUTHENTICATION_UNIFIED_CONSENT_UNIFIED_CONSENT_CONSTANTS_H_
+#define IOS_CHROME_BROWSER_UI_AUTHENTICATION_UNIFIED_CONSENT_UNIFIED_CONSENT_CONSTANTS_H_
+
+#import <Foundation/Foundation.h>
+
+// Accessibility identifier to open the advanced sign-in settings view.
+extern NSString* const kAdvancedSigninSettingsLinkIdentifier;
+// Accessibility identifier for |-UnifiedConsentViewController.view|.
+extern NSString* const kUnifiedConsentScrollViewIdentifier;
+
+#endif  // IOS_CHROME_BROWSER_UI_AUTHENTICATION_UNIFIED_CONSENT_UNIFIED_CONSENT_CONSTANTS_H_

ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.mm

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+NSString* const kAdvancedSigninSettingsLinkIdentifier =
+    @"AdvancedSigninSettingsLinkIdentifier";
+NSString* const kUnifiedConsentScrollViewIdentifier =
+    @"kUnifiedConsentScrollViewIdentifier";

ios/chrome/browser/ui/authentication/unified_consent/unified_consent_view_controller.h

@@ -9,10 +9,7 @@
 
 #include <vector>
 
-// Accessibility identifier to open the advanced sign-in settings view.
-extern NSString* const kAdvancedSigninSettingsLinkIdentifier;
-// Accessibility identifier for |-UnifiedConsentViewController.view|.
-extern NSString* const kUnifiedConsentScrollViewIdentifier;
+#import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h"
 
 @protocol UnifiedConsentViewControllerDelegate;
 

ios/chrome/browser/ui/authentication/unified_consent/unified_consent_view_controller.mm

@@ -9,6 +9,7 @@
 #include "ios/chrome/browser/application_context.h"
 #import "ios/chrome/browser/ui/authentication/authentication_constants.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/identity_picker_view.h"
+#import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_constants.h"
 #import "ios/chrome/browser/ui/authentication/unified_consent/unified_consent_view_controller_delegate.h"
 #import "ios/chrome/browser/ui/colors/MDCPalette+CrAdditions.h"
 #import "ios/chrome/browser/ui/util/label_link_controller.h"
@@ -26,11 +27,6 @@
 #error "This file requires ARC support."
 #endif
 
-NSString* const kAdvancedSigninSettingsLinkIdentifier =
-    @"AdvancedSigninSettingsLinkIdentifier";
-NSString* const kUnifiedConsentScrollViewIdentifier =
-    @"kUnifiedConsentScrollViewIdentifier";
-
 namespace {
 
 // Vertical margin the main title and the identity picker.