Fix a concurrency bug that ends up in a crash.

Bug: 18085768
Change-Id: I016bec997787839526ddfc521ebb99d0c7b05189
diff --git a/java/src/com/android/inputmethod/latin/RichInputConnection.java b/java/src/com/android/inputmethod/latin/RichInputConnection.java
index a3f7bb4..a9df216 100644
--- a/java/src/com/android/inputmethod/latin/RichInputConnection.java
+++ b/java/src/com/android/inputmethod/latin/RichInputConnection.java
@@ -369,7 +369,9 @@
         }
         // This never calls InputConnection#getCapsMode - in fact, it's a static method that
         // never blocks or initiates IPC.
-        return CapsModeUtils.getCapsMode(mCommittedTextBeforeComposingText, inputType,
+        // TODO: don't call #toString() here. Instead, all accesses to
+        // mCommittedTextBeforeComposingText should be done on the main thread.
+        return CapsModeUtils.getCapsMode(mCommittedTextBeforeComposingText.toString(), inputType,
                 spacingAndPunctuations, hasSpaceBefore);
     }