[iOS] Remove legacy sign-in view

This CL remove all the code and resources used by the legacy sign-in
view as they are no longer used.

Bug: 1407658

Change-Id: Id0d38cb90a19b52b89189af9eeddd043d3222a80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4184205
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1096167}

ios/chrome/app/strings/ios_chromium_strings.grd

@@ -297,9 +297,6 @@ locale.  The strings in this file are specific to iOS.
       <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_SHORT" desc="Subtitle of the screen suggesting to the user to sign in. [iOS only]">
           Sign in to get the most out of Chromium.
       </message>
-      <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_MANAGED" desc="Subtitle of the screen suggesting to the user to sign in when their Sign In is managed by their administrator.">
-          Sign in to Chromium
-      </message>
       <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_SIGNIN_FORCED" desc="Subtitle of a dialog to sign in to Chrome when sign-in is required because of an enterprise policy. [iOS only]">
         Your organization requires you to sign in to use Chromium.
       </message>

ios/chrome/app/strings/ios_google_chrome_strings.grd

@@ -297,9 +297,6 @@ locale.  The strings in this file are specific to iOS.
       <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_SHORT" desc="Subtitle of the screen suggesting to the user to sign in. [iOS only]">
           Sign in to get the most out of Chrome.
       </message>
-      <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_MANAGED" desc="Subtitle of the screen suggesting to the user to sign in when their Sign In is managed by their administrator.">
-          Sign in to Chrome
-      </message>
       <message name="IDS_IOS_FIRST_RUN_SIGNIN_SUBTITLE_SIGNIN_FORCED" desc="Subtitle of a dialog to sign in to Chrome when sign-in is required because of an enterprise policy. [iOS only]">
         Your organization requires you to sign in to use Chrome.
       </message>

ios/chrome/browser/ui/authentication/signin/forced_signin/BUILD.gn

@@ -18,7 +18,6 @@ source_set("forced_signin") {
     "//ios/chrome/browser/ui/authentication/signin:signin_protected",
     "//ios/chrome/browser/ui/first_run:screen_delegate",
     "//ios/chrome/browser/ui/first_run:utils",
-    "//ios/chrome/browser/ui/first_run/legacy_signin",
     "//ios/chrome/browser/ui/first_run/signin",
     "//ios/chrome/browser/ui/screen:screen_provider",
     "//ios/chrome/browser/ui/screen:screen_type",

ios/chrome/browser/ui/authentication/signin/forced_signin/forced_signin_coordinator.mm

@@ -15,7 +15,6 @@
 #import "ios/chrome/browser/ui/authentication/signin/signin_coordinator+protected.h"
 #import "ios/chrome/browser/ui/first_run/first_run_screen_delegate.h"
 #import "ios/chrome/browser/ui/first_run/first_run_util.h"
-#import "ios/chrome/browser/ui/first_run/legacy_signin/legacy_signin_screen_coordinator.h"
 #import "ios/chrome/browser/ui/first_run/signin/signin_screen_coordinator.h"
 #import "ios/chrome/browser/ui/screen/screen_provider.h"
 #import "ios/chrome/browser/ui/screen/screen_type.h"
@@ -110,11 +109,6 @@ - (void)presentScreen:(ScreenType)type {
 - (InterruptibleChromeCoordinator*)createChildCoordinatorWithScreenType:
     (ScreenType)type {
   switch (type) {
-    case kLegacySignIn_DEPRECATED:
-      return [[LegacySigninScreenCoordinator alloc]
-          initWithBaseNavigationController:self.navigationController
-                                   browser:self.browser
-                                  delegate:self];
     case kSignIn:
       return [[SigninScreenCoordinator alloc]
           initWithBaseNavigationController:self.navigationController

ios/chrome/browser/ui/first_run/BUILD.gn

@@ -91,7 +91,6 @@ source_set("first_run") {
     "//ios/chrome/browser/ui/elements:elements_internal",
     "//ios/chrome/browser/ui/fancy_ui",
     "//ios/chrome/browser/ui/first_run/default_browser",
-    "//ios/chrome/browser/ui/first_run/legacy_signin",
     "//ios/chrome/browser/ui/first_run/signin",
     "//ios/chrome/browser/ui/first_run/tangible_sync",
     "//ios/chrome/browser/ui/first_run/welcome",

ios/chrome/browser/ui/first_run/first_run_coordinator.mm

@@ -16,7 +16,6 @@
 #import "ios/chrome/browser/ui/first_run/default_browser/default_browser_screen_coordinator.h"
 #import "ios/chrome/browser/ui/first_run/first_run_screen_delegate.h"
 #import "ios/chrome/browser/ui/first_run/first_run_util.h"
-#import "ios/chrome/browser/ui/first_run/legacy_signin/legacy_signin_screen_coordinator.h"
 #import "ios/chrome/browser/ui/first_run/signin/signin_screen_coordinator.h"
 #import "ios/chrome/browser/ui/first_run/tangible_sync/tangible_sync_screen_coordinator.h"
 #import "ios/chrome/browser/ui/first_run/welcome/welcome_screen_coordinator.h"
@@ -150,11 +149,6 @@ - (ChromeCoordinator*)createChildCoordinatorWithScreenType:(ScreenType)type {
           initWithBaseNavigationController:self.navigationController
                                    browser:self.browser
                                   delegate:self];
-    case kLegacySignIn_DEPRECATED:
-      return [[LegacySigninScreenCoordinator alloc]
-          initWithBaseNavigationController:self.navigationController
-                                   browser:self.browser
-                                  delegate:self];
     case kDefaultBrowserPromo:
       return [[DefaultBrowserScreenCoordinator alloc]
           initWithBaseNavigationController:self.navigationController