Add API for device owner to switch users

Once verified that caller is device owner just calls through to
the activity manager and acts like that call.

Change-Id: I34023313cd6742b73d2105655ec6b631879aa37a

api/current.txt

@@ -5330,6 +5330,7 @@ package android.app.admin {
     method public void setRestrictionsProvider(android.content.ComponentName, android.content.ComponentName);
     method public void setSecureSetting(android.content.ComponentName, java.lang.String, java.lang.String);
     method public int setStorageEncryption(android.content.ComponentName, boolean);
+    method public boolean switchUser(android.content.ComponentName, android.os.UserHandle);
     method public void uninstallCaCert(android.content.ComponentName, byte[]);
     method public void wipeData(int);
     field public static final java.lang.String ACTION_ADD_DEVICE_ADMIN = "android.app.action.ADD_DEVICE_ADMIN";

core/java/android/app/admin/DevicePolicyManager.java

@@ -2374,6 +2374,24 @@ public class DevicePolicyManager {
         }
     }
 
+    /**
+     * Called by a device owner to switch the specified user to the foreground.
+     *
+     * @param admin Which {@link DeviceAdminReceiver} this request is associated with.
+     * @param userHandle the user to switch to; null will switch to primary.
+     * @return {@code true} if the switch was successful, {@code false} otherwise.
+     *
+     * @see Intent#ACTION_USER_FOREGROUND
+     */
+    public boolean switchUser(ComponentName admin, UserHandle userHandle) {
+        try {
+            return mService.switchUser(admin, userHandle);
+        } catch (RemoteException re) {
+            Log.w(TAG, "Could not switch user ", re);
+            return false;
+        }
+    }
+
     /**
      * Called by a profile or device owner to get the application restrictions for a given target
      * application running in the managed profile.

core/java/android/app/admin/IDevicePolicyManager.aidl

@@ -139,6 +139,7 @@ interface IDevicePolicyManager {
     UserHandle createUser(in ComponentName who, in String name);
     UserHandle createAndInitializeUser(in ComponentName who, in String name, in String profileOwnerName, in ComponentName profileOwnerComponent, in Bundle adminExtras);
     boolean removeUser(in ComponentName who, in UserHandle userHandle);
+    boolean switchUser(in ComponentName who, in UserHandle userHandle);
 
     void setAccountManagementDisabled(in ComponentName who, in String accountType, in boolean disabled);
     String[] getAccountTypesWithManagementDisabled();

services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java

@@ -3591,6 +3591,30 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {
         }
     }
 
+    @Override
+    public boolean switchUser(ComponentName who, UserHandle userHandle) {
+        synchronized (this) {
+            if (who == null) {
+                throw new NullPointerException("ComponentName is null");
+            }
+            getActiveAdminForCallerLocked(who, DeviceAdminInfo.USES_POLICY_DEVICE_OWNER);
+
+            long id = Binder.clearCallingIdentity();
+            try {
+                int userId = UserHandle.USER_OWNER;
+                if (userHandle != null) {
+                    userId = userHandle.getIdentifier();
+                }
+                return ActivityManagerNative.getDefault().switchUser(userId);
+            } catch (RemoteException e) {
+                Log.e(LOG_TAG, "Couldn't switch user", e);
+                return false;
+            } finally {
+                restoreCallingIdentity(id);
+            }
+        }
+    }
+
     @Override
     public Bundle getApplicationRestrictions(ComponentName who, String packageName) {
         final UserHandle userHandle = new UserHandle(UserHandle.getCallingUserId());