Add conversion from Handle to UntypedHandle

mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java

Index: mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java
diff --git a/mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java b/mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java
index 39d17f4652b10eb6bd26c6401342ce386c82b9ec..be3c70663e5be191f4481d588e15808d4b52b6aa 100644
--- a/mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java
+++ b/mojo/android/system/src/org/chromium/mojo/system/CoreImpl.java
@@ -208,7 +208,7 @@ public class CoreImpl implements Core, AsyncWaiter {
         if (handles != null) {
             for (Handle handle : handles) {
                 if (handle.isValid()) {
-                    ((HandleImpl) handle).invalidateHandle();
+                    ((HandleBase) handle).invalidateHandle();
                 }
             }
         }
@@ -387,7 +387,7 @@ public class CoreImpl implements Core, AsyncWaiter {
      */
     private int getMojoHandle(Handle handle) {
         if (handle.isValid()) {
-            return ((HandleImpl) handle).getMojoHandle();
+            return ((HandleBase) handle).getMojoHandle();
         }
         return 0;
     }