Add drawer with state information

platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerApplication.java

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 package org.skia.viewer;
 
 import android.app.Application;
 
 public class ViewerApplication extends Application {
     private long mNativeHandle = 0;
     private ViewerActivity mViewerActivity;
+    private String mStateJsonStr, mTitle;
 
     static {
         System.loadLibrary("skia_android");
         System.loadLibrary("viewer");
     }
 
     private native long createNativeApp();
     private native void destroyNativeApp(long handle);
 
     @Override
     public void onCreate() {
         super.onCreate();
         mNativeHandle = createNativeApp();
     }
 
     @Override
     public void onTerminate() {
         if (mNativeHandle != 0) {
             destroyNativeApp(mNativeHandle);
             mNativeHandle = 0;
         }
         super.onTerminate();
     }
 
     public long getNativeHandle() {
         return mNativeHandle;
     }
 
     public void setViewerActivity(ViewerActivity viewerActivity) {
-        this.mViewerActivity = viewerActivity;
+        mViewerActivity = viewerActivity;
+        // Note that viewerActivity might be null (called by onDestroy)
+        if (mViewerActivity != null) {
+            // A new ViewerActivity is created; initialize its state and title
+            if (mStateJsonStr != null) {
+                mViewerActivity.setState(mStateJsonStr);
+            }
+            if (mTitle != null) {
+                mViewerActivity.setTitle(mTitle);
+            }
+        }
     }
 
     public void setTitle(String title) {
-        final String finalTitle = title;
+        mTitle = title; // Similar to mStateJsonStr, we have to store this.
         if (mViewerActivity != null) {
             mViewerActivity.runOnUiThread(new Runnable() {
                 @Override
                 public void run() {
-                    mViewerActivity.setTitle(finalTitle);
+                    mViewerActivity.setTitle(mTitle);
                 }
             });
         }
+    }
+
+    public void setState(String stateJsonStr) {
+        // We have to store this state because ViewerActivity may be destroyed while the native app
+        // is still running. When a new ViewerActivity is created, we'll pass the state to it.
+        mStateJsonStr = stateJsonStr;
+        if (mViewerActivity != null) {
+            mViewerActivity.runOnUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    mViewerActivity.setState(mStateJsonStr);
+                }
+            });
+        }
     }
 }