Revert "Add a new test case for |AssistantManagerServiceImpl|."

This reverts commit 64cf44e2.

Reason for revert: Tentative suspect for
DriveIntegrationServiceWithGaiaDisabledBrowserTest.DriveDisabled
linux-chromeos-chrome browser_test failure
https://ci.chromium.org/p/chrome/builders/ci/linux-chromeos-chrome/3090

Original change's description:
> Add a new test case for |AssistantManagerServiceImpl|.
> 
> This CL adds a new test case to ensure we update the supported action
> list stored in |AssistantManagerServiceImpl| when ambient mode state has
> changed.
> 
> Bug: b/149237062
> Test: run the new unit test added in this change.
> 
> Change-Id: Idc3c538e023cb59e76fb6c71219e4846da6d9c30
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1969777
> Commit-Queue: Meilin Wang <meilinw@chromium.org>
> Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#740817}

TBR=xiaohuic@chromium.org,meilinw@chromium.org,jeroendh@google.com

Change-Id: I596dc72fa1422ee85925f2616557dfbb9b705bad
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/149237062, 1051728
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2053283Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740893}

chromeos/services/assistant/assistant_manager_service_impl.cc

@@ -314,6 +314,9 @@ void AssistantManagerServiceImpl::SetAccessToken(
 }
 
 void AssistantManagerServiceImpl::EnableAmbientMode(bool enabled) {
+  if (!assistant_manager_)
+    return;
+
   // Update |action_module_| accordingly, as some actions, e.g. open URL
   // in the browser, are not supported in ambient mode.
   action_module_->SetAmbientModeEnabled(enabled);
@@ -457,8 +460,6 @@ void AssistantManagerServiceImpl::SyncDeviceAppsStatus() {
 }
 
 void AssistantManagerServiceImpl::StartVoiceInteraction() {
-  DCHECK(assistant_manager_);
-
   platform_api_->SetMicState(true);
   assistant_manager_->StartAssistantInteraction();
 }
@@ -478,7 +479,7 @@ void AssistantManagerServiceImpl::StopActiveInteraction(
 void AssistantManagerServiceImpl::StartWarmerWelcomeInteraction(
     int num_warmer_welcome_triggered,
     bool allow_tts) {
-  DCHECK(assistant_manager_internal_);
+  DCHECK(assistant_manager_internal_ != nullptr);
 
   const std::string interaction =
       CreateWarmerWelcomeInteraction(num_warmer_welcome_triggered);

chromeos/services/assistant/assistant_manager_service_impl.h

@@ -235,11 +235,6 @@ class COMPONENT_EXPORT(ASSISTANT_SERVICE) AssistantManagerServiceImpl
   // thread is finished.
   void WaitUntilStartIsFinishedForTesting();
 
-  // Get the action module for testing.
-  action::CrosActionModule* action_module_for_testing() {
-    return action_module_.get();
-  }
-
  private:
   class AssistantMediaSessionObserver;
   void StartAssistantInternal(const base::Optional<std::string>& access_token);

chromeos/services/assistant/assistant_manager_service_impl_unittest.cc

@@ -221,10 +221,6 @@ class AssistantManagerServiceImplTest : public testing::Test {
     return delegate_->assistant_manager_internal();
   }
 
-  action::CrosActionModule* action_module() {
-    return assistant_manager_service_->action_module_for_testing();
-  }
-
   void Start() {
     assistant_manager_service()->Start("dummy-access-token",
                                        /*enable_hotword=*/false);
@@ -546,16 +542,5 @@ TEST_F(AssistantManagerServiceImplTest,
   Start();
 }
 
-TEST_F(AssistantManagerServiceImplTest,
-       ShouldUpdateActionModuleWhenAmbientModeStateChanged) {
-  EXPECT_FALSE(action_module()->IsAmbientModeEnabledForTesting());
-
-  assistant_manager_service()->EnableAmbientMode(true);
-  EXPECT_TRUE(action_module()->IsAmbientModeEnabledForTesting());
-
-  assistant_manager_service()->EnableAmbientMode(false);
-  EXPECT_FALSE(action_module()->IsAmbientModeEnabledForTesting());
-}
-
 }  // namespace assistant
 }  // namespace chromeos