[Android] Expose showFileChooser in AwContentsClient interface

android_webview/java/src/org/chromium/android_webview/AwWebContentsDelegate.java

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.android_webview;
 
+import com.google.common.annotations.VisibleForTesting;
+
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.components.web_contents_delegate_android.WebContentsDelegateAndroid;
 
 /**
  * WebView-specific WebContentsDelegate.
  * This file is the Java version of the native class of the same name.
  * It should contain abstract WebContentsDelegate methods to be implemented by the embedder.
  * These methods belong to WebView but are not shared with the Chromium Android port.
  */
+@VisibleForTesting
 @JNINamespace("android_webview")
 public abstract class AwWebContentsDelegate extends WebContentsDelegateAndroid {
+    // Callback filesSelectedInChooser() when done.
+    @CalledByNative
+    public abstract void runFileChooser(int processId, int renderId, int mode_flags,
+            String acceptTypes, String title, String defaultFilename,  boolean capture);
+
     @CalledByNative
     public abstract boolean addNewContents(boolean isDialog, boolean isUserGesture);
 
     @CalledByNative
     public abstract void closeContents();
 
     @CalledByNative
     public abstract void activateContents();
 
     /**
      * Report a change in the preferred size.
      * @param width preferred width in CSS pixels.
      * @param height scroll height of the document element in CSS pixels.
      */
     @CalledByNative
     public void updatePreferredSize(int widthCss, int heightCss) {
     }
+
+    // Call in response to a prior runFileChooser call.
+    protected static native void nativeFilesSelectedInChooser(int processId, int renderId,
+            int mode_flags, String[] filePath);
 }