[Device Service] Port ScreenOrientationListener into Device Service.

services/device/screen_orientation/screen_orientation_listener_android.cc

Index: services/device/screen_orientation/screen_orientation_listener_android.cc
diff --git a/services/device/screen_orientation/screen_orientation_listener_android.cc b/services/device/screen_orientation/screen_orientation_listener_android.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0c863d8b699f0e0646ba57f02e85e916fc5774f3
--- /dev/null
+++ b/services/device/screen_orientation/screen_orientation_listener_android.cc
@@ -0,0 +1,58 @@
+// Copyright 2017 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/device/screen_orientation/screen_orientation_listener_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/message_loop/message_loop.h"
+#include "jni/ScreenOrientationListener_jni.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace device {
+
+// static
+void ScreenOrientationListenerAndroid::Create(
+    mojom::ScreenOrientationListenerRequest request) {
+  mojo::MakeStrongBinding(

[leonhsl(Using Gerrit), 2017/03/09 08:22:31]

ScreenOrientationListenerAndroid lives on IO thread, one instance per Renderer
Process. This is the same behavior with before.

+      base::WrapUnique(new ScreenOrientationListenerAndroid()),
+      std::move(request));
+}
+
+ScreenOrientationListenerAndroid::ScreenOrientationListenerAndroid()
+    : listeners_count_(0) {}
+
+ScreenOrientationListenerAndroid::~ScreenOrientationListenerAndroid() {
+  DCHECK(base::MessageLoopForIO::IsCurrent());
+  if (listeners_count_ > 0) {
+    Java_ScreenOrientationListener_startAccurateListening(
+        base::android::AttachCurrentThread());
+  }
+}
+
+void ScreenOrientationListenerAndroid::Start() {
+  DCHECK(base::MessageLoopForIO::IsCurrent());
+  ++listeners_count_;
+  if (listeners_count_ == 1) {
+    // Ask the ScreenOrientationListener (Java) to start accurately listening to
+    // the screen orientation. It keep track of the number of start request if
+    // it is already running an accurate listening.
+    Java_ScreenOrientationListener_startAccurateListening(
+        base::android::AttachCurrentThread());
+  }
+}
+
+void ScreenOrientationListenerAndroid::Stop() {
+  DCHECK(base::MessageLoopForIO::IsCurrent());
+  DCHECK(listeners_count_ > 0);
+  --listeners_count_;
+  if (listeners_count_ == 0) {
+    // Ask the ScreenOrientationListener (Java) to stop accurately listening to
+    // the screen orientation. It will actually stop only if the number of stop
+    // requests matches the number of start requests.
+    Java_ScreenOrientationListener_stopAccurateListening(
+        base::android::AttachCurrentThread());
+  }
+}
+
+}  // namespace device