DO NOT MERGE: add interim startDream api.

DreamManager#startDream has been updated on QPR and master which removes
the unnecessary component name parameter, but it breaks TM CTS tests.
The interim api added in this change will prevent breakage on TM, and
should not be merged downstream.

Test: atest DreamManagerServiceTests
Fix: 245223722
Fix: 245058392
Fix: 245070240
Change-Id: Id9e8cc67003da9fc3e03bffd6ec50643d10652b5

core/api/test-current.txt

@@ -287,6 +287,7 @@ package android.app {
     method @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE) public void setDreamOverlay(@Nullable android.content.ComponentName);
     method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public void setScreensaverEnabled(boolean);
     method @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE) public void setSystemDreamComponent(@Nullable android.content.ComponentName);
+    method @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE) public void startDream(@Nullable android.content.ComponentName);
     method @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE) public void startDream();
     method @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE) public void stopDream();
   }

core/java/android/app/DreamManager.java

@@ -84,6 +84,25 @@ public class DreamManager {
                 com.android.internal.R.bool.config_dreamsSupported);
     }
 
+    /**
+     * Starts dreaming.
+     *
+     * This API is equivalent to {@link DreamManager#startDream()} but with a nullable component
+     * name to be compatible with TM CTS tests.
+     *
+     * <p>This is only used for testing the dream service APIs.
+     *
+     * @see DreamManager#startDream()
+     *
+     * @hide
+     */
+    @TestApi
+    @UserHandleAware
+    @RequiresPermission(android.Manifest.permission.WRITE_DREAM_STATE)
+    public void startDream(@Nullable ComponentName name) {
+        startDream();
+    }
+
     /**
      * Starts dreaming.
      *