Fix WindowAndroid leak in Android WebView

ui/android/window_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 "ui/android/window_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "jni/WindowAndroid_jni.h"
 #include "ui/android/window_android_compositor.h"
 #include "ui/android/window_android_observer.h"
 
 namespace ui {
 
 using base::android::AttachCurrentThread;
 using base::android::ScopedJavaLocalRef;
 
-WindowAndroid::WindowAndroid(JNIEnv* env, jobject obj)
-  : weak_java_window_(env, obj), compositor_(NULL) {
+WindowAndroid::WindowAndroid(JNIEnv* env, jobject obj) : compositor_(NULL) {
+  java_window_.Reset(env, obj);
 }
 
 void WindowAndroid::Destroy(JNIEnv* env, jobject obj) {
   delete this;
 }
 
 ScopedJavaLocalRef<jobject> WindowAndroid::GetJavaObject() {
-  return weak_java_window_.get(AttachCurrentThread());
+  return base::android::ScopedJavaLocalRef<jobject>(java_window_);
 }
 
 bool WindowAndroid::RegisterWindowAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 WindowAndroid::~WindowAndroid() {
   DCHECK(!compositor_);
 }
 
@@ skipping 25 matching lines @@
 void WindowAndroid::DetachCompositor() {
   compositor_ = NULL;
   FOR_EACH_OBSERVER(WindowAndroidObserver,
                     observer_list_,
                     OnDetachCompositor());
   observer_list_.Clear();
 }
 
 void WindowAndroid::RequestVSyncUpdate() {
   JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobject> obj = GetJavaObject();
-  if (obj.is_null())
-    return;
-  Java_WindowAndroid_requestVSyncUpdate(env, obj.obj());
+  Java_WindowAndroid_requestVSyncUpdate(env, GetJavaObject().obj());
 }
 
 void WindowAndroid::SetNeedsAnimate() {
   if (compositor_)
     compositor_->SetNeedsAnimate();
 }
 
 void WindowAndroid::Animate(base::TimeTicks begin_frame_time) {
   FOR_EACH_OBSERVER(
       WindowAndroidObserver, observer_list_, OnAnimate(begin_frame_time));
@@ skipping 17 matching lines @@
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------
 
 jlong Init(JNIEnv* env, jobject obj) {
   WindowAndroid* window = new WindowAndroid(env, obj);
   return reinterpret_cast<intptr_t>(window);
 }
 
 }  // namespace ui