Added missing case to the switch and removed lint suppression

chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java

Index: chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java b/chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java
index 71591b9c5871fdb945e610015a4b216a70a721bf..b545e8177948046899b54b1c531bbdddd8b97f3c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/signin/ConfirmSyncDataStateMachine.java
@@ -4,7 +4,6 @@
 
 package org.chromium.chrome.browser.signin;
 
-import android.annotation.SuppressLint;
 import android.app.DialogFragment;
 import android.app.Fragment;
 import android.app.FragmentManager;
@@ -133,8 +132,6 @@ public class ConfirmSyncDataStateMachine
      * entire flow is over, if it is answered positively one of the onConfirm functions is called
      * and this function is called again.
      */
-    // TODO(crbug.com/635567): Fix this properly.
-    @SuppressLint("SwitchIntDef")
     private void progress() {
         switch (mState) {
             case BEFORE_OLD_ACCOUNT_DIALOG:
@@ -187,8 +184,8 @@ public class ConfirmSyncDataStateMachine
                 mState = DONE;
                 mCallback.onConfirm(mWipeData);
                 break;
-            default:
-                assert false : "Invalid state: " + mState;
+            case DONE:
+                throw new IllegalStateException("Can't progress from DONE state!");
         }
     }