Introdude IC#deleteSurroundingTextInCodePoints().

This CL introduces a API variant of IC#deleteSurroundingText(), named
IC#deleteSurroundingTextInCodePoints().  Major differences from
the existing one are:
  - The lengths are supplied in code points rather than code units.
  - This API does nothing if there are one or more invalid surrogate
    pairs in the requested range.  (Failure Atomicity)

Note that due to the asynchronous nature of the input method
architecture in Android, implementing the same logic in the input method
side basically ends up with unreliable and unpredictable results.

Bug: 6526420
Change-Id: I7f6a2c5d3d52079ae71623fd5e40d60c688dd5fb
diff --git a/core/java/com/android/internal/view/IInputConnectionWrapper.java b/core/java/com/android/internal/view/IInputConnectionWrapper.java
index 85ec29c..b77cc63 100644
--- a/core/java/com/android/internal/view/IInputConnectionWrapper.java
+++ b/core/java/com/android/internal/view/IInputConnectionWrapper.java
@@ -49,6 +49,7 @@
     private static final int DO_FINISH_COMPOSING_TEXT = 65;
     private static final int DO_SEND_KEY_EVENT = 70;
     private static final int DO_DELETE_SURROUNDING_TEXT = 80;
+    private static final int DO_DELETE_SURROUNDING_TEXT_IN_CODE_POINTS = 81;
     private static final int DO_BEGIN_BATCH_EDIT = 90;
     private static final int DO_END_BATCH_EDIT = 95;
     private static final int DO_REPORT_FULLSCREEN_MODE = 100;
@@ -155,9 +156,14 @@
         dispatchMessage(obtainMessageII(DO_CLEAR_META_KEY_STATES, states, 0));
     }
 
-    public void deleteSurroundingText(int leftLength, int rightLength) {
+    public void deleteSurroundingText(int beforeLength, int afterLength) {
         dispatchMessage(obtainMessageII(DO_DELETE_SURROUNDING_TEXT,
-            leftLength, rightLength));
+                beforeLength, afterLength));
+    }
+
+    public void deleteSurroundingTextInCodePoints(int beforeLength, int afterLength) {
+        dispatchMessage(obtainMessageII(DO_DELETE_SURROUNDING_TEXT_IN_CODE_POINTS,
+                beforeLength, afterLength));
     }
 
     public void beginBatchEdit() {
@@ -389,6 +395,15 @@
                 ic.deleteSurroundingText(msg.arg1, msg.arg2);
                 return;
             }
+            case DO_DELETE_SURROUNDING_TEXT_IN_CODE_POINTS: {
+                InputConnection ic = mInputConnection.get();
+                if (ic == null || !isActive()) {
+                    Log.w(TAG, "deleteSurroundingTextInCodePoints on inactive InputConnection");
+                    return;
+                }
+                ic.deleteSurroundingTextInCodePoints(msg.arg1, msg.arg2);
+                return;
+            }
             case DO_BEGIN_BATCH_EDIT: {
                 InputConnection ic = mInputConnection.get();
                 if (ic == null || !isActive()) {
@@ -454,7 +469,7 @@
     Message obtainMessageII(int what, int arg1, int arg2) {
         return mH.obtainMessage(what, arg1, arg2);
     }
-    
+
     Message obtainMessageO(int what, Object arg1) {
         return mH.obtainMessage(what, 0, 0, arg1);
     }