[Mojo Video Capture] Introduce abstraction BuildableVideoCaptureDevice

content/browser/renderer_host/media/buildable_video_capture_device.h

Index: content/browser/renderer_host/media/buildable_video_capture_device.h
diff --git a/content/browser/renderer_host/media/buildable_video_capture_device.h b/content/browser/renderer_host/media/buildable_video_capture_device.h
new file mode 100644
index 0000000000000000000000000000000000000000..7ea3d9fe2758d01f8fe8daaf121e0115fec5129a
--- /dev/null
+++ b/content/browser/renderer_host/media/buildable_video_capture_device.h
@@ -0,0 +1,74 @@
+// 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_
+
+#include "base/memory/ptr_util.h"
+#include "base/memory/ref_counted.h"
+#include "content/public/common/media_stream_request.h"
+#include "media/capture/video/video_capture_device.h"
+#include "media/capture/video_capture_types.h"
+
+namespace content {
+
+class VideoCaptureController;
+
+class CONTENT_EXPORT BuildableDeviceCallbacks {

[mcasas, 2017/03/22 00:33:42]

Why not make this class
class BuildableVideoCaptureDevice{
 public:
  class Callbacks {
  };

?

[chfremer, 2017/03/22 17:26:51]

The reason why I generally avoid nesting interfaces like this is that it forces
the class implementing the nested interface to know about the outer interface,
even when it has no need to know about it.

Done.

+ public:
+  virtual ~BuildableDeviceCallbacks() {}
+  // Returns false if no descriptor was found.

[mcasas, 2017/03/22 00:33:42]

s/false/nullptr/?

[chfremer, 2017/03/22 17:26:51]

Done.

+  virtual const media::VideoCaptureDeviceDescriptor* LookupDeviceDescriptor(
+      const std::string& id) = 0;
+  virtual void WillStartDevice(media::VideoFacingMode facing_mode) = 0;
+  virtual void DidStartDevice(VideoCaptureController* controller) = 0;
+  virtual void OnDeviceStartFailed(VideoCaptureController* controller) = 0;

[mcasas, 2017/03/22 00:33:42]

These two methods are used similarly, so what about
s/DidStartDevice/OnDeviceStartSucceed/
and
s/OnDeviceStartFailed/OnDeviceStartFailed/
or somesuch?

[chfremer, 2017/03/22 17:26:51]

We currently have names WillStartDevice() and DidStartDevice() as per miu's
suggestion and in line with other places in Chromium, see comments in PatchSet2.
Note that I am planning to straighten out the naming in CL18, see
https://codereview.chromium.org/2769543002/diff/20001/content/browser/rendere...

+};
+
+// Abstraction for a video capture device that must be "built" before it can be
+// operated and must be "stopped", before it can be released. Typical operation
+// is that a newly created instance initially reports IsDeviceAlive() == false.
+// Clients call CreateAndStartDeviceAsync(), which kicks off the asynchronous
+// building of the device. The outcome of the device building is typically
+// reported to an instance of BuildableDeviceCallbacks (see above). Once the
+// device has been built successfully, the "Device operation methods", are
+// allowed to be called. ReleaseDeviceAsync() must be called in order to
+// release the device if it has before been built successfully. After calling
+// ReleaseDeviceAsync(), it is legal to call CreateAndStartDeviceAsync() to
+// rebuild and start the device again.
+class BuildableVideoCaptureDevice {
+ public:
+  virtual ~BuildableVideoCaptureDevice() {}
+
+  // Device management methods.
+  virtual void CreateAndStartDeviceAsync(
+      VideoCaptureController* controller,
+      const media::VideoCaptureParams& params,
+      BuildableDeviceCallbacks* callbacks,
+      base::OnceClosure done_cb) = 0;
+  virtual void ReleaseDeviceAsync(VideoCaptureController* controller,
+                                  base::OnceClosure done_cb) = 0;
+  virtual bool IsDeviceAlive() const = 0;
+
+  // Device operation methods.
+  virtual void GetPhotoCapabilities(
+      media::VideoCaptureDevice::GetPhotoCapabilitiesCallback callback)
+      const = 0;
+  virtual void SetPhotoOptions(
+      media::mojom::PhotoSettingsPtr settings,
+      media::VideoCaptureDevice::SetPhotoOptionsCallback callback) = 0;
+  virtual void TakePhoto(
+      media::VideoCaptureDevice::TakePhotoCallback callback) = 0;
+  virtual void MaybeSuspendDevice() = 0;
+  virtual void ResumeDevice() = 0;
+  virtual void RequestRefreshFrame() = 0;
+
+  // Methods for specific types of devices.
+  virtual void SetDesktopCaptureWindowIdAsync(gfx::NativeViewId window_id,
+                                              base::OnceClosure done_cb) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_BUILDABLE_VIDEO_CAPTURE_DEVICE_H_