Add support for a virtual display on ChromeOS

chrome/browser/media/desktop_media_list_ash.cc

Index: chrome/browser/media/desktop_media_list_ash.cc
diff --git a/chrome/browser/media/desktop_media_list_ash.cc b/chrome/browser/media/desktop_media_list_ash.cc
index d24ec21b2b1c493942bb5472bfe57dacb2610b98..f788aa911a247f21e9ecbf3514b1ad9f6126bd33 100644
--- a/chrome/browser/media/desktop_media_list_ash.cc
+++ b/chrome/browser/media/desktop_media_list_ash.cc
@@ -6,11 +6,14 @@
 
 #include <set>
 
+#include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "base/hash.h"
 #include "base/logging.h"
+#include "base/memory/singleton.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/sys_info.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/media/desktop_media_list_observer.h"
 #include "chrome/grit/generated_resources.h"
@@ -18,6 +21,8 @@
 #include "media/base/video_util.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/compositor/dip_util.h"
+#include "ui/display/chromeos/display_configurator.h"
+#include "ui/gfx/display_observer.h"
 #include "ui/gfx/image/image.h"
 #include "ui/snapshot/snapshot.h"
 
@@ -29,6 +34,58 @@ namespace {
 // Update the list twice per second.
 const int kDefaultUpdatePeriod = 500;
 
+#if defined(OS_CHROMEOS)
+// Watches for the creation of a virtual display and updates
+// DesktopMediaID::AuraWindowRegistry.
+class VirtualScreenMonitor : public gfx::DisplayObserver {
+ public:
+  VirtualScreenMonitor();
+  ~VirtualScreenMonitor();
+
+  // gfx::DisplayObserver overrides:
+  void OnDisplayAdded(const gfx::Display& display) override;
+  void OnDisplayRemoved(const gfx::Display& display) override {}
+  void OnDisplayMetricsChanged(const gfx::Display& display,
+                               uint32_t metrics) override {}
+
+  // static
+  static VirtualScreenMonitor* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<VirtualScreenMonitor>;
+
+  DISALLOW_COPY_AND_ASSIGN(VirtualScreenMonitor);
+};
+
+VirtualScreenMonitor::VirtualScreenMonitor() {
+  gfx::Screen::GetNativeScreen()->AddObserver(this);
+}
+
+VirtualScreenMonitor::~VirtualScreenMonitor() {
+}
+
+// Subsequent observers (e.g. from the VirtualDisplayCapturer class) will see
+// the updated virtual screen window as the observers are called in the order
+// they are added.
+void VirtualScreenMonitor::OnDisplayAdded(const gfx::Display& display) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  if (display.id() ==
+      ui::DisplayConfigurator::GetInstance()->GetVirtualDisplayId()) {
+    aura::Window* window = ash::Shell::GetInstance()
+                               ->display_controller()
+                               ->GetRootWindowForDisplayId(display.id());
+
+    content::DesktopMediaID::RegisterVirtualScreenAuraWindow(window);
+  }
+}
+
+// static
+VirtualScreenMonitor* VirtualScreenMonitor::GetInstance() {
+  return Singleton<VirtualScreenMonitor>::get();
+}
+
+#endif  // defined(OS_CHROMEOS)
+
 }  // namespace
 
 DesktopMediaListAsh::SourceDescription::SourceDescription(
@@ -209,6 +266,26 @@ void DesktopMediaListAsh::EnumerateSources(
           sources, root_windows[i], ash::kShellWindowId_DockedContainer);
     }
   }
+#if defined(OS_CHROMEOS)
+  // DisplayConfigurator only works when running on ChromeOS.
+  if (base::SysInfo::IsRunningOnChromeOS()) {
+    if (ui::DisplayConfigurator::GetInstance()->GetVirtualDisplayId() ==
+        gfx::Display::kInvalidDisplayID) {
+      // Instantiate the VirtualScreenMonitor object which will observe for
+      // the virtual display being created and store the window so that it can
+      // be looked up from the content::DesktopMediaID.
+      (void)VirtualScreenMonitor::GetInstance();
+      SourceDescription virtual_screen_source(
+          content::DesktopMediaID(
+              content::DesktopMediaID::TYPE_AURA_VIRTUAL_SCREEN, 0),
+          l10n_util::GetStringUTF16(
+              IDS_DESTOP_MEDIA_PICKER_VIRTUAL_SCREEN_NAME));
+      sources->push_back(virtual_screen_source);
+      // TODO(robert.bradford): crbug.com/425060 There is no thumbnail for the
+      // virtual screen right now.
+    }
+  }
+#endif  // defined(OS_CHROMEOS)
 }
 
 void DesktopMediaListAsh::CaptureThumbnail(content::DesktopMediaID id,