Upstream chromium side of modal dialogs for webview.

android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java

Index: android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java
diff --git a/android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java b/android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java
index 630efe2dc6374f02f1bb8dfdd3fda895481983a7..bd1809ca7efe8a0c8c8e6811c0982f372254c888 100644
--- a/android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java
+++ b/android_webview/javatests/src/org/chromium/android_webview/test/NullContentsClient.java
@@ -4,11 +4,14 @@
 
 package org.chromium.android_webview.test;
 
+import android.content.Context;
 import android.view.KeyEvent;
 import android.webkit.ConsoleMessage;
 
 import org.chromium.android_webview.AwContentsClient;
 import org.chromium.android_webview.AwHttpAuthHandler;
+import org.chromium.android_webview.JsPromptResultReceiver;
+import org.chromium.android_webview.JsResultReceiver;
 
 /**
  * As a convience for tests that only care about specefic callbacks, this class provides
@@ -37,4 +40,21 @@ class NullContentsClient extends AwContentsClient {
     public void onReceivedHttpAuthRequest(AwHttpAuthHandler handler, String host, String realm) {
         handler.cancel();
     }
-};
+
+    @Override
+    public void handleJsAlert(String url, String message, JsResultReceiver receiver) {
+    }
+
+    @Override
+    public void handleJsBeforeUnload(String url, String message, JsResultReceiver receiver) {
+    }
+
+    @Override
+    public void handleJsConfirm(String url, String message, JsResultReceiver receiver) {
+    }
+
+    @Override
+    public void handleJsPrompt(
+            String url, String message, String defaultValue, JsPromptResultReceiver receiver) {
+    }
+}