Revert "Enable Assistant for child accounts."

This reverts commit 7c4d25d6e89687033e6234fcf8bb018dee54a193.

Reason for revert: feature punted to M74

Bug: 914210

Original change's description:
> Enable Assistant for child accounts.
>
> This reverts commit 71f820a1783a9ce31f78bea9971c7b4256507bb2 ("Disable assistant for child account").
>
> Bug: b:120075638
> Test: built and tested locally
> Change-Id: I59d3d4869ba596fa462a904b8a64a88230c28325
> Reviewed-on: https://chromium-review.googlesource.com/c/1351155
> Commit-Queue: Henrique Nazaré Santos <nazare@google.com>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
> Reviewed-by: Sam McNally <sammc@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#613206}

TBR=xiyuan@chromium.org,sammc@chromium.org,xiaohuic@chromium.org,nazare@google.com

Bug: b:120075638
Change-Id: I452fba75870677ec70fc3d1bcec3ab433c5361fd
Reviewed-on: https://chromium-review.googlesource.com/c/1447270
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/branch-heads/3683@{#84}
Cr-Branched-From: e51029943e0a38dd794b73caaf6373d5496ae783-refs/heads/master@{#625896}
diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index adf15ef8..664de71d5 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -709,6 +709,7 @@
     case mojom::AssistantAllowedState::DISALLOWED_BY_ARC_DISALLOWED:
     case mojom::AssistantAllowedState::DISALLOWED_BY_FLAG:
     case mojom::AssistantAllowedState::DISALLOWED_BY_SUPERVISED_USER:
+    case mojom::AssistantAllowedState::DISALLOWED_BY_CHILD_USER:
     case mojom::AssistantAllowedState::DISALLOWED_BY_INCOGNITO:
       // TODO(xiaohuic): show a specific toast.
       return;
diff --git a/ash/public/interfaces/voice_interaction_controller.mojom b/ash/public/interfaces/voice_interaction_controller.mojom
index 04589e3..ccada86 100644
--- a/ash/public/interfaces/voice_interaction_controller.mojom
+++ b/ash/public/interfaces/voice_interaction_controller.mojom
@@ -39,6 +39,8 @@
   DISALLOWED_BY_NONPRIMARY_USER,
   // Disallowed because current user is supervised user.
   DISALLOWED_BY_SUPERVISED_USER,
+  // Disallowed because current user is child user.
+  DISALLOWED_BY_CHILD_USER,
   // Disallowed because incognito mode.
   DISALLOWED_BY_INCOGNITO,
   // Disallowed because the device is in demo mode.
diff --git a/chrome/browser/chromeos/arc/arc_util.cc b/chrome/browser/chromeos/arc/arc_util.cc
index 386f330..21284a6 100644
--- a/chrome/browser/chromeos/arc/arc_util.cc
+++ b/chrome/browser/chromeos/arc/arc_util.cc
@@ -597,6 +597,9 @@
   if (profile->IsLegacySupervised())
     return ash::mojom::AssistantAllowedState::DISALLOWED_BY_SUPERVISED_USER;
 
+  if (profile->IsChild())
+    return ash::mojom::AssistantAllowedState::DISALLOWED_BY_CHILD_USER;
+
   if (chromeos::DemoSession::IsDeviceInDemoMode())
     return ash::mojom::AssistantAllowedState::DISALLOWED_BY_DEMO_MODE;
 
diff --git a/chrome/browser/chromeos/arc/arc_util_unittest.cc b/chrome/browser/chromeos/arc/arc_util_unittest.cc
index 426c5ad..c3d89df 100644
--- a/chrome/browser/chromeos/arc/arc_util_unittest.cc
+++ b/chrome/browser/chromeos/arc/arc_util_unittest.cc
@@ -29,6 +29,7 @@
 #include "chrome/browser/policy/profile_policy_connector.h"
 #include "chrome/browser/policy/profile_policy_connector_factory.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/supervised_user/supervised_user_constants.h"
 #include "chrome/test/base/testing_browser_process.h"
 #include "chrome/test/base/testing_profile.h"
 #include "chrome/test/base/testing_profile_manager.h"
@@ -531,6 +532,18 @@
             IsAssistantAllowedForProfile(profile()));
 }
 
+TEST_F(ChromeArcUtilTest, IsAssistantAllowedForProfile_ChildUser) {
+  base::CommandLine::ForCurrentProcess()->InitFromArgv(
+      {"", "--arc-availability=officially-supported",
+       "--enable-voice-interaction"});
+  ScopedLogIn login(GetFakeUserManager(),
+                    AccountId::FromUserEmailGaiaId(
+                        profile()->GetProfileUserName(), kTestGaiaId));
+  profile()->SetSupervisedUserId(supervised_users::kChildAccountSUID);
+  EXPECT_EQ(ash::mojom::AssistantAllowedState::DISALLOWED_BY_CHILD_USER,
+            IsAssistantAllowedForProfile(profile()));
+}
+
 TEST_F(ChromeArcUtilTest, IsAssistantAllowedForProfile_Locale) {
   profile()->GetTestingPrefService()->SetString(
       language::prefs::kApplicationLocale, "he");