Shift+Meta+Space should reverse-rotate subtypes.

This is a follow up CL to my previous CL [1], which added a new key
binding Meta+Space to rotate enabled IME subtypes.  With this CL,
Shift+Meta+Space starts reverse-rotating enabled IME subtypes as
originally planed.

 [1]: I4005692215edfcf8bed3e86b1e07000148f986f5
      ae61f7118a92e097e854c840d5726c0920f5db0e

Bug: 25753404
Bug: 28103839
Change-Id: I3694edd80be6dfe18b90360e24ae4d451b331928
diff --git a/services/core/java/com/android/server/InputMethodManagerService.java b/services/core/java/com/android/server/InputMethodManagerService.java
index ac7872a..58e3674 100644
--- a/services/core/java/com/android/server/InputMethodManagerService.java
+++ b/services/core/java/com/android/server/InputMethodManagerService.java
@@ -2546,7 +2546,8 @@
                 return false;
             }
             final ImeSubtypeListItem nextSubtype = mSwitchingController.getNextInputMethodLocked(
-                    onlyCurrentIme, mMethodMap.get(mCurMethodId), mCurrentSubtype);
+                    onlyCurrentIme, mMethodMap.get(mCurMethodId), mCurrentSubtype,
+                    true /* forward */);
             if (nextSubtype == null) {
                 return false;
             }
@@ -2569,7 +2570,8 @@
                 return false;
             }
             final ImeSubtypeListItem nextSubtype = mSwitchingController.getNextInputMethodLocked(
-                    false /* onlyCurrentIme */, mMethodMap.get(mCurMethodId), mCurrentSubtype);
+                    false /* onlyCurrentIme */, mMethodMap.get(mCurMethodId), mCurrentSubtype,
+                    true /* forward */);
             if (nextSubtype == null) {
                 return false;
             }
@@ -2963,9 +2965,8 @@
 
     private void handleSwitchInputMethod(final boolean forwardDirection) {
         synchronized (mMethodMap) {
-            // TODO: Support forwardDirection.
             final ImeSubtypeListItem nextSubtype = mSwitchingController.getNextInputMethodLocked(
-                    false, mMethodMap.get(mCurMethodId), mCurrentSubtype);
+                    false, mMethodMap.get(mCurMethodId), mCurrentSubtype, forwardDirection);
             if (nextSubtype == null) {
                 return;
             }