Make the C++ PlatformViewportAndroid's dtor call the Java PVA's destroy() method.

services/native_viewport/platform_viewport_android.cc

 // Copyright 2013 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.
 
 #include "services/native_viewport/platform_viewport_android.h"
 
 #include <android/input.h>
 #include <android/native_window_jni.h>
 
 #include "base/android/jni_android.h"
@@ skipping 43 matching lines @@
 PlatformViewportAndroid::PlatformViewportAndroid(Delegate* delegate)
     : delegate_(delegate),
       window_(NULL),
       id_generator_(0),
       weak_factory_(this) {
 }
 
 PlatformViewportAndroid::~PlatformViewportAndroid() {
   if (window_)
     ReleaseWindow();
+  if (!java_platform_viewport_android_.is_empty()) {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    Java_PlatformViewportAndroid_detach(
+        env, java_platform_viewport_android_.get(env).obj());
+  }
 }
 
 void PlatformViewportAndroid::Destroy(JNIEnv* env, jobject obj) {
   delegate_->OnDestroyed();
 }
 
 void PlatformViewportAndroid::SurfaceCreated(JNIEnv* env,
                                              jobject obj,
                                              jobject jsurface) {
   base::android::ScopedJavaLocalRef<jobject> protector(env, jsurface);
@@ skipping 80 matching lines @@
     delegate_->OnEvent(mojo::Event::From(char_event));
   }
   return true;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformViewportAndroid, PlatformViewport implementation:
 
 void PlatformViewportAndroid::Init(const gfx::Rect& bounds) {
   JNIEnv* env = base::android::AttachCurrentThread();
-  Java_PlatformViewportAndroid_createForActivity(
-      env,
-      base::android::GetApplicationContext(),
-      reinterpret_cast<jlong>(this));
+  java_platform_viewport_android_ = JavaObjectWeakGlobalRef(
+      env, Java_PlatformViewportAndroid_createForActivity(
+               env, base::android::GetApplicationContext(),
+               reinterpret_cast<jlong>(this)).obj());
 }
 
 void PlatformViewportAndroid::Show() {
   // Nothing to do. View is created visible.
 }
 
 void PlatformViewportAndroid::Hide() {
   // Nothing to do. View is always visible.
 }
 
@@ skipping 23 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformViewport, public:
 
 // static
 scoped_ptr<PlatformViewport> PlatformViewport::Create(Delegate* delegate) {
   return scoped_ptr<PlatformViewport>(
       new PlatformViewportAndroid(delegate)).Pass();
 }
 
 }  // namespace native_viewport