Upstream chromium side of modal dialogs for webview.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 0481380996096e2664edfce53789d9d95776f335..6f5164d937e0bd58b3da3b4e999eb47b88f7045d 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -120,6 +120,27 @@ public class AwContents {
         mContentsClient.onReceivedHttpAuthRequest(handler, host, realm);
     }
 
+    @CalledByNative
+    private void handleJsAlert(String url, String message, JsResultReceiver receiver) {
+        mContentsClient.handleJsAlert(url, message, receiver);
+    }
+
+    @CalledByNative
+    private void handleJsBeforeUnload(String url, String message, JsResultReceiver receiver) {
+        mContentsClient.handleJsBeforeUnload(url, message, receiver);
+    }
+
+    @CalledByNative
+    private void handleJsConfirm(String url, String message, JsResultReceiver receiver) {
+        mContentsClient.handleJsConfirm(url, message, receiver);
+    }
+
+    @CalledByNative
+    private void handleJsPrompt(String url, String message, String defaultValue,
+            JsPromptResultReceiver receiver) {
+        mContentsClient.handleJsPrompt(url, message, defaultValue, receiver);
+    }
+
     //--------------------------------------------------------------------------------------------
     //  Native methods
     //--------------------------------------------------------------------------------------------