Revert of [Mojo Video Capture] Introduce abstraction VideoCaptureSystem

content/browser/renderer_host/media/video_capture_manager.h

Index: content/browser/renderer_host/media/video_capture_manager.h
diff --git a/content/browser/renderer_host/media/video_capture_manager.h b/content/browser/renderer_host/media/video_capture_manager.h
index 10e0c62aba40e82ccaab8b69684d0e47df9f2d77..a6fe9c4597bfc3ee56b6d82087b73551c0b6c34f 100644
--- a/content/browser/renderer_host/media/video_capture_manager.h
+++ b/content/browser/renderer_host/media/video_capture_manager.h
@@ -34,8 +34,6 @@
 #include "media/base/video_facing.h"
 #include "media/capture/video/video_capture_device.h"
 #include "media/capture/video/video_capture_device_factory.h"
-#include "media/capture/video/video_capture_device_info.h"
-#include "media/capture/video/video_capture_system.h"
 #include "media/capture/video_capture_types.h"
 
 #if defined(OS_ANDROID)
@@ -58,7 +56,7 @@
       base::Callback<void(const base::WeakPtr<VideoCaptureController>&)>;
 
   VideoCaptureManager(
-      std::unique_ptr<media::VideoCaptureSystem> capture_system,
+      std::unique_ptr<media::VideoCaptureDeviceFactory> factory,
       scoped_refptr<base::SingleThreadTaskRunner> device_task_runner);
 
   // AddVideoCaptureObserver() can be called only before any devices are opened.
@@ -165,7 +163,7 @@
 
   // Gets a weak reference to the device factory, used for tests.
   media::VideoCaptureDeviceFactory* video_capture_device_factory() const {
-    return video_capture_system_->video_capture_device_factory();
+    return video_capture_device_factory_.get();
   }
 
 #if defined(OS_WIN)
@@ -199,12 +197,13 @@
 
   using EnumerationCallback =
       base::Callback<void(const media::VideoCaptureDeviceDescriptors&)>;
-  // Asynchronously obtains descriptors for the available devices.
-  // As a side-effect, updates |devices_info_cache_|.
   void EnumerateDevices(const EnumerationCallback& client_callback);
 
   // Implementation of BuildableVideoCaptureDevice::Callbacks:
-  void OnDeviceStarted(VideoCaptureController* controller) override;
+  const media::VideoCaptureDeviceDescriptor* LookupDeviceDescriptor(
+      const std::string& id) override;
+  void WillStartDevice(media::VideoFacingMode facing_mode) override;
+  void DidStartDevice(VideoCaptureController* controller) override;
   void OnDeviceStartFailed(VideoCaptureController* controller) override;
   void OnDeviceStartAborted() override;
 
@@ -217,24 +216,32 @@
 
  private:
   class CaptureDeviceStartRequest;
+  struct DeviceInfo;
 
   using SessionMap = std::map<media::VideoCaptureSessionId, MediaStreamDevice>;
+  using DeviceInfos = std::vector<DeviceInfo>;
   using DeviceStartQueue = std::list<CaptureDeviceStartRequest>;
   using VideoCaptureDeviceDescriptor = media::VideoCaptureDeviceDescriptor;
   using VideoCaptureDeviceDescriptors = media::VideoCaptureDeviceDescriptors;
 
   ~VideoCaptureManager() override;
-
-  void OnDeviceInfosReceived(
-      base::ElapsedTimer* timer,
-      const EnumerationCallback& client_callback,
-      const std::vector<media::VideoCaptureDeviceInfo>& device_infos);
 
   // Helpers to report an event to our Listener.
   void OnOpened(MediaStreamType type,
                 media::VideoCaptureSessionId capture_session_id);
   void OnClosed(MediaStreamType type,
                 media::VideoCaptureSessionId capture_session_id);
+  void OnDevicesInfoEnumerated(base::ElapsedTimer* timer,
+                               const EnumerationCallback& client_callback,
+                               const DeviceInfos& new_devices_info_cache);
+
+  // Consolidates the cached devices list with the list of currently connected
+  // devices in the system |names_snapshot|. Retrieves the supported formats of
+  // the new devices and sends the new cache to OnDevicesInfoEnumerated().
+  void ConsolidateDevicesInfoOnDeviceThread(
+      base::Callback<void(const DeviceInfos&)> on_devices_enumerated_callback,
+      const DeviceInfos& old_device_info_cache,
+      std::unique_ptr<VideoCaptureDeviceDescriptors> descriptors_snapshot);
 
   // Checks to see if |controller| has no clients left. If so, remove it from
   // the list of controllers, and delete it asynchronously. |controller| may be
@@ -253,7 +260,7 @@
       VideoCaptureController* controller) const;
 
   // Finds the device info by |id| in |devices_info_cache_|, or nullptr.
-  media::VideoCaptureDeviceInfo* GetDeviceInfoById(const std::string& id);
+  DeviceInfo* GetDeviceInfoById(const std::string& id);
 
   // Finds a VideoCaptureController for the indicated |capture_session_id|,
   // creating a fresh one if necessary. Returns nullptr if said
@@ -311,14 +318,19 @@
 
   // Device creation factory injected on construction from MediaStreamManager or
   // from the test harness.
-  std::unique_ptr<media::VideoCaptureSystem> video_capture_system_;
+  std::unique_ptr<media::VideoCaptureDeviceFactory>
+      video_capture_device_factory_;
 
   base::ObserverList<media::VideoCaptureObserver> capture_observers_;
 
-  // Local cache of the enumerated DeviceInfos. GetDeviceSupportedFormats() will
+  // Local cache of the enumerated video capture devices' names and capture
+  // supported formats. A snapshot of the current devices and their capabilities
+  // is composed in VideoCaptureDeviceFactory::EnumerateDeviceNames() and
+  // ConsolidateDevicesInfoOnDeviceThread(), and this snapshot is used to update
+  // this list in OnDevicesInfoEnumerated(). GetDeviceSupportedFormats() will
   // use this list if the device is not started, otherwise it will retrieve the
   // active device capture format from the VideoCaptureController associated.
-  std::vector<media::VideoCaptureDeviceInfo> devices_info_cache_;
+  DeviceInfos devices_info_cache_;
 
   // Map used by DesktopCapture.
   std::map<media::VideoCaptureSessionId, gfx::NativeViewId>