media: add video capture device for ARC++ camera HAL v3

media/capture/video/chromeos/display_rotation_observer.cc

+// 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 "media/capture/video/chromeos/display_rotation_observer.h"
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/threading/thread_task_runner_handle.h"
+
+namespace media {
+
+ScreenObserverDelegate::ScreenObserverDelegate(
+    DisplayRotationObserver* observer,
+    scoped_refptr<base::SingleThreadTaskRunner> display_task_runner)
+    : observer_(observer),
+      display_task_runner_(std::move(display_task_runner)),
+      delegate_task_runner_(base::ThreadTaskRunnerHandle::Get()) {
+  display_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ScreenObserverDelegate::AddObserverOnDisplayThread, this));
+}
+
+void ScreenObserverDelegate::RemoveObserver() {
+  DCHECK(delegate_task_runner_->BelongsToCurrentThread());
+  observer_ = NULL;
+  display_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ScreenObserverDelegate::RemoveObserverOnDisplayThread, this));
+}
+
+ScreenObserverDelegate::~ScreenObserverDelegate() {
+  DCHECK(!observer_);
+}
+
+void ScreenObserverDelegate::OnDisplayAdded(
+    const display::Display& /*new_display*/) {}
+
+void ScreenObserverDelegate::OnDisplayRemoved(
+    const display::Display& /*old_display*/) {}
+
+void ScreenObserverDelegate::OnDisplayMetricsChanged(
+    const display::Display& display,
+    uint32_t metrics) {
+  DCHECK(display_task_runner_->BelongsToCurrentThread());
+  if (!(metrics & DISPLAY_METRIC_ROTATION))
+    return;
+  SendDisplayRotation(display);
+}
+
+void ScreenObserverDelegate::AddObserverOnDisplayThread() {
+  DCHECK(display_task_runner_->BelongsToCurrentThread());
+  display::Screen* screen = display::Screen::GetScreen();
+  if (screen) {
+    screen->AddObserver(this);
+    SendDisplayRotation(screen->GetPrimaryDisplay());
+  }
+}
+
+void ScreenObserverDelegate::RemoveObserverOnDisplayThread() {
+  DCHECK(display_task_runner_->BelongsToCurrentThread());
+  display::Screen* screen = display::Screen::GetScreen();
+  if (screen) {
+    screen->RemoveObserver(this);
+  }
+}
+
+// Post the screen rotation change from the UI thread to capture thread
+void ScreenObserverDelegate::SendDisplayRotation(
+    const display::Display& display) {
+  DCHECK(display_task_runner_->BelongsToCurrentThread());
+  delegate_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ScreenObserverDelegate::SendDisplayRotationOnCaptureThread,
+                 this, display));
+}
+
+void ScreenObserverDelegate::SendDisplayRotationOnCaptureThread(
+    const display::Display& display) {
+  DCHECK(delegate_task_runner_->BelongsToCurrentThread());
+  if (observer_)
+    observer_->SetDisplayRotation(display);
+}
+
+}  // namespace media