Dependency.get(BG_HANDLER) is dead. Long live @BgHandler.

Bug: 9755874
Test: atest SystemUITests
Change-Id: I3fd4f9e72e7917041786a4c823fe5824fa49916b
diff --git a/packages/SystemUI/src/com/android/systemui/Dependency.java b/packages/SystemUI/src/com/android/systemui/Dependency.java
index 1a0690c..a616484 100644
--- a/packages/SystemUI/src/com/android/systemui/Dependency.java
+++ b/packages/SystemUI/src/com/android/systemui/Dependency.java
@@ -163,10 +163,6 @@
      */
     private static final String BG_LOOPER_NAME = "background_looper";
     /**
-     * Key for getting a background Handler for background work.
-     */
-    private static final String BG_HANDLER_NAME = "background_handler";
-    /**
      * Key for getting a Handler for receiving time tick broadcasts on.
      */
     public static final String TIME_TICK_HANDLER_NAME = "time_tick_handler";
@@ -195,10 +191,6 @@
      */
     public static final DependencyKey<Looper> MAIN_LOOPER = new DependencyKey<>(MAIN_LOOPER_NAME);
     /**
-     * Key for getting a background Handler for background work.
-     */
-    public static final DependencyKey<Handler> BG_HANDLER = new DependencyKey<>(BG_HANDLER_NAME);
-    /**
      * Key for getting a Handler for receiving time tick broadcasts on.
      */
     public static final DependencyKey<Handler> TIME_TICK_HANDLER =
@@ -347,7 +339,6 @@
         // on imports.
         mProviders.put(TIME_TICK_HANDLER, mTimeTickHandler::get);
         mProviders.put(BG_LOOPER, mBgLooper::get);
-        mProviders.put(BG_HANDLER, mBgHandler::get);
         mProviders.put(MAIN_LOOPER, mMainLooper::get);
         mProviders.put(MAIN_HANDLER, mMainHandler::get);
         mProviders.put(ActivityStarter.class, mActivityStarter::get);
diff --git a/packages/SystemUI/tests/src/com/android/systemui/privacy/PrivacyItemControllerTest.kt b/packages/SystemUI/tests/src/com/android/systemui/privacy/PrivacyItemControllerTest.kt
index 098521f..20148e1 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/privacy/PrivacyItemControllerTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/privacy/PrivacyItemControllerTest.kt
@@ -110,7 +110,6 @@
         handler = Handler(testableLooper.looper)
 
         appOpsController = mDependency.injectMockDependency(AppOpsController::class.java)
-        mDependency.injectTestDependency(Dependency.BG_HANDLER, handler)
         mDependency.injectTestDependency(Dependency.MAIN_HANDLER, handler)
         mContext.addMockSystemService(UserManager::class.java, userManager)
         mContext.getOrCreateTestableResources().addOverride(R.string.device_services,