Remove java ViewAndroid class

content/browser/power_save_blocker_android.cc

 // 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.
 
-#include "content/browser/power_save_blocker_android.h"
-
-#include "base/android/jni_android.h"
-#include "base/android/jni_weak_ref.h"
 #include "base/logging.h"
+#include "content/browser/android/content_view_core_impl.h"
 #include "content/browser/power_save_blocker_impl.h"
+#include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/browser_thread.h"
-#include "jni/PowerSaveBlocker_jni.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "ui/android/view_android.h"
 
-using base::android::AttachCurrentThread;
-using base::android::ScopedJavaLocalRef;
-using gfx::NativeView;
-
 namespace content {
 
 class PowerSaveBlockerImpl::Delegate
-    : public base::RefCountedThreadSafe<PowerSaveBlockerImpl::Delegate> {
+    : public base::RefCountedThreadSafe<PowerSaveBlockerImpl::Delegate>,
+      public WebContentsObserver {
  public:
-  explicit Delegate(NativeView view_android) {
-    j_view_android_ = JavaObjectWeakGlobalRef(
-        AttachCurrentThread(), view_android->GetJavaObject().obj());
-  }
+  explicit Delegate(WebContents* web_contents);
 
   // Does the actual work to apply or remove the desired power save block.
   void ApplyBlock();
   void RemoveBlock();
 
  private:
   friend class base::RefCountedThreadSafe<Delegate>;
-  ~Delegate() {}
+  ~Delegate() override;
 
-  JavaObjectWeakGlobalRef j_view_android_;
+  ContentViewCoreImpl* GetContentViewCore();
 
   DISALLOW_COPY_AND_ASSIGN(Delegate);
 };
 
+PowerSaveBlockerImpl::Delegate::Delegate(WebContents* web_contents)
+    : WebContentsObserver(web_contents) {
+}
+
+PowerSaveBlockerImpl::Delegate::~Delegate() {
+}
+
 void PowerSaveBlockerImpl::Delegate::ApplyBlock() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobject> j_object = j_view_android_.get(env);
-  if (j_object.obj())
-    Java_PowerSaveBlocker_applyBlock(env, j_object.obj());
+  ContentViewCoreImpl* content_view_core_impl = GetContentViewCore();
+  if (!content_view_core_impl)
+    return;
+  content_view_core_impl->IncrementKeepScreenOnCount();
 }
 
 void PowerSaveBlockerImpl::Delegate::RemoveBlock() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobject> j_object = j_view_android_.get(env);
-  if (j_object.obj())
-    Java_PowerSaveBlocker_removeBlock(env, j_object.obj());
+  ContentViewCoreImpl* content_view_core_impl = GetContentViewCore();
+  if (!content_view_core_impl)
+    return;
+  content_view_core_impl->DecrementKeepScreenOnCount();
+}
+
+ContentViewCoreImpl* PowerSaveBlockerImpl::Delegate::GetContentViewCore() {
+  if (!web_contents())

[Ted C, 2015/04/06 20:56:11]

it took me a second to see why this needed to be a WebContentsObserver but it is
because of web_contents() doing the right thing.

I guess the screen on count dies when a CVC dies right?  Since the view we use
for the power check is added via the view delegate.

[boliu, 2015/04/06 21:04:06]

No in general, but yes in practice on android.

PowerSaveBlocker is a content/public api that's not tied to the life time of any
other content object (and it doesn't work on android, since android needs the
special InitDisplaySleepBlocker method).

The existing code is still dangerous because it used to hold a raw pointer to
the ViewAndroid across a PostTask. If CVC.destroy is called after the task is
posted but before it runs, then it leads to a UAF.

+    return nullptr;
+  return ContentViewCoreImpl::FromWebContents(web_contents());
 }
 
 PowerSaveBlockerImpl::PowerSaveBlockerImpl(PowerSaveBlockerType type,
                                            Reason reason,
                                            const std::string& description) {
   // Don't support kPowerSaveBlockPreventAppSuspension
 }
 
 PowerSaveBlockerImpl::~PowerSaveBlockerImpl() {
   if (delegate_.get()) {
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
         base::Bind(&Delegate::RemoveBlock, delegate_));
   }
 }
 
-void PowerSaveBlockerImpl::InitDisplaySleepBlocker(NativeView view_android) {
-  if (!view_android)
+void PowerSaveBlockerImpl::InitDisplaySleepBlocker(WebContents* web_contents) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (!web_contents)
     return;
 
-  delegate_ = new Delegate(view_android);
-  // This may be called on any thread.
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(&Delegate::ApplyBlock, delegate_));
-}
-
-bool RegisterPowerSaveBlocker(JNIEnv* env) {
-  return RegisterNativesImpl(env);
+  delegate_ = new Delegate(web_contents);
+  delegate_->ApplyBlock();
 }
 
 }  // namespace content