Add support for a virtual display on ChromeOS

content/browser/media/capture/desktop_capture_device_aura.cc

Index: content/browser/media/capture/desktop_capture_device_aura.cc
diff --git a/content/browser/media/capture/desktop_capture_device_aura.cc b/content/browser/media/capture/desktop_capture_device_aura.cc
index 1b26d4c1823cc59653b2c2706f3fb86f8c32128e..79c59cbd24d397b889d78e61a1db09ca8e4103ee 100644
--- a/content/browser/media/capture/desktop_capture_device_aura.cc
+++ b/content/browser/media/capture/desktop_capture_device_aura.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/sys_info.h"
 #include "base/timer/timer.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
@@ -28,8 +29,16 @@
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer.h"
+#include "ui/gfx/display.h"
+#include "ui/gfx/display_observer.h"
 #include "ui/gfx/screen.h"
 
+#if defined(USE_ASH)
+#include "ash/display/display_controller.h"

[piman, 2015/02/24 01:58:29]

content/ is not allowed to depend on ash/

+#include "ash/shell.h"
+#include "ui/display/chromeos/display_configurator.h"
+#endif
+
 namespace content {
 
 namespace {
@@ -93,6 +102,7 @@ class DesktopVideoCaptureMachine
     : public VideoCaptureMachine,
       public aura::WindowObserver,
       public ui::CompositorObserver,
+      public gfx::DisplayObserver,
       public base::SupportsWeakPtr<DesktopVideoCaptureMachine> {
  public:
   DesktopVideoCaptureMachine(const DesktopMediaID& source);
@@ -121,6 +131,12 @@ class DesktopVideoCaptureMachine
   void OnCompositingLockStateChanged(ui::Compositor* compositor) override {}
   void OnCompositingShuttingDown(ui::Compositor* compositor) override {}
 
+  // Implements gfx::DisplayObserver.
+  void OnDisplayAdded(const gfx::Display& new_display) override;
+  void OnDisplayRemoved(const gfx::Display& old_display) override {}
+  void OnDisplayMetricsChanged(const gfx::Display& display,
+                               uint32_t changed_metrics) override {}
+
  private:
   // Captures a frame.
   // |dirty| is false for timer polls and true for compositor updates.
@@ -152,6 +168,9 @@ class DesktopVideoCaptureMachine
   // Clears cursor state.
   void ClearCursorState();
 
+  // Start the capture after setup.
+  void StartCapture();
+
   // The window associated with the desktop.
   aura::Window* desktop_window_;
 
@@ -190,24 +209,7 @@ DesktopVideoCaptureMachine::DesktopVideoCaptureMachine(
 
 DesktopVideoCaptureMachine::~DesktopVideoCaptureMachine() {}
 
-bool DesktopVideoCaptureMachine::Start(
-    const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
-    const media::VideoCaptureParams& params) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  desktop_window_ = content::DesktopMediaID::GetAuraWindowById(window_id_);
-  if (!desktop_window_)
-    return false;
-
-  // If the associated layer is already destroyed then return failure.
-  ui::Layer* layer = desktop_window_->layer();
-  if (!layer)
-    return false;
-
-  DCHECK(oracle_proxy.get());
-  oracle_proxy_ = oracle_proxy;
-  capture_params_ = params;
-
+void DesktopVideoCaptureMachine::StartCapture() {
   // Update capture size.
   UpdateCaptureSize();
 
@@ -226,6 +228,43 @@ bool DesktopVideoCaptureMachine::Start(
   timer_.Start(FROM_HERE, oracle_proxy_->min_capture_period(),
                base::Bind(&DesktopVideoCaptureMachine::Capture, AsWeakPtr(),
                           false));
+}
+
+bool DesktopVideoCaptureMachine::Start(

[Sergey Ulanov, 2015/02/23 23:16:12]

Can the virtual-screen logic be moved out of this class? I think it can be
implemented as follows:
  - Change DesktopVideoCaptureMachine constructor to take aura::Window instead
of DesktopMediaID.
  - Change DesktopCaptureDeviceAura constructor to take aura::Window instead of
DesktopMediaID.
  - Add a new class called e.g. VirtualScreenCapturer that implements
media::VideoCaptureDevice and wraps DesktopCaptureDeviceAura, which actually
captures frames.

That way you will need fewer ifdefs and the code will be easier to read.

[oshima, 2015/02/24 19:43:21]

and please move ash code from content/.

[robert.bradford, 2015/03/03 19:58:00]

I've started working on the non virtual display refactoring here:
https://codereview.chromium.org/974513002/

+    const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+    const media::VideoCaptureParams& params) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  capture_params_ = params;
+  DCHECK(oracle_proxy.get());
+  oracle_proxy_ = oracle_proxy;
+
+#if defined(USE_ASH)

[oshima, 2015/02/24 19:43:21]

no USE_ASH in content/. You probably should just use OS_CHROMEOS because this
won't work on win ash.

+  // Window for virtual display is available asynchronously after request. The
+  // DisplayObserver on the screen will be notified of the new display and
+  // Window and start the capture.
+  if (window_id_.type == DesktopMediaID::TYPE_AURA_VIRTUAL_SCREEN) {
+    DCHECK(base::SysInfo::IsRunningOnChromeOS());
+    ui::DisplayConfigurator* configurator =
+        ash::Shell::GetInstance()->display_configurator();
+    gfx::Screen::GetNativeScreen()->AddObserver(this);
+    configurator->EnableVirtualDisplay(make_scoped_ptr(
+        new ui::DisplayMode(params.requested_format.frame_size, false, 60)));
+    return true;
+  }
+#else
+  desktop_window_ = content::DesktopMediaID::GetAuraWindowById(window_id_);
+#endif
+
+  if (!desktop_window_)
+    return false;
+
+  // If the associated layer is already destroyed then return failure.
+  ui::Layer* layer = desktop_window_->layer();
+  if (!layer)
+    return false;
+
+  StartCapture();
 
   return true;
 }
@@ -244,6 +283,13 @@ void DesktopVideoCaptureMachine::Stop(const base::Closure& callback) {
     desktop_window_ = NULL;
   }
 
+#if defined(USE_ASH)
+  if (window_id_.type == DesktopMediaID::TYPE_AURA_VIRTUAL_SCREEN) {
+    gfx::Screen::GetNativeScreen()->RemoveObserver(this);
+    ash::Shell::GetInstance()->display_configurator()->DisableVirtualDisplay();
+  }
+#endif
+
   // Stop timer.
   timer_.Stop();
 
@@ -507,6 +553,30 @@ void DesktopVideoCaptureMachine::OnCompositingEnded(
       &DesktopVideoCaptureMachine::Capture, AsWeakPtr(), true));
 }
 
+void DesktopVideoCaptureMachine::OnDisplayAdded(
+    const gfx::Display& new_display) {
+#if defined(USE_ASH)
+  DCHECK(base::SysInfo::IsRunningOnChromeOS());
+  ui::DisplayConfigurator* configurator =
+      ash::Shell::GetInstance()->display_configurator();
+  int64 display_id = configurator->GetVirtualDisplayId();
+
+  if (display_id == new_display.id()) {
+    desktop_window_ = ash::Shell::GetInstance()
+                          ->display_controller()
+                          ->GetRootWindowForDisplayId(display_id);
+
+    // We only need the observer for a short time.
+    gfx::Screen::GetNativeScreen()->RemoveObserver(this);
+
+    if (desktop_window_ && desktop_window_->layer()) {
+      StartCapture();
+    } else {
+      Stop(base::Bind(&base::DoNothing));
+    }
+  }
+}
+#endif
 }  // namespace
 
 DesktopCaptureDeviceAura::DesktopCaptureDeviceAura(