Media Stream Image Capture (4): wire takePhoto and implement in FakeVCDevice

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index e8c23abce0aa7e5a1a4d2480de8e5c991a1ac471..8bd1bc4bc13eb92f0a812d4d39aae7c0c4415592 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -597,6 +597,21 @@ void MediaStreamManager::StopStreamDevice(int render_process_id,
   }
 }
 
+int MediaStreamManager::VideoDeviceIdToSessionId(

[miu, 2016/05/04 23:45:50]

The device_id is mapped to a session_id, and then in VideoCaptureManager, the
session_id isn't needed to get at the DeviceEntry. Instead of making any changes
to MediaStreamManager, just add a search-for-DeviceEntry-by-device_id to
VideoCaptureManager::TakePhoto().

[mcasas, 2016/05/05 00:57:12]

I wish it was that simple. The MSM has a map from
renderer device ID to sessions, which I use in VCM 
to get to the VCM device ID associated to the session,
_but_ these are different device ids ! Also, the session
in MSM is different from the session in VCM !

E.g. the Renderer Device ID can be called a 128 uuid ID:
ea6a5c2fa17cdee8ff26b13681a3d42b2083cae66ce647e73450ad38a18c6c16
whereas VCM calls this guy
DJH5266R8QBG1HPBV

[miu, 2016/05/05 22:04:24]

OIC. One more thought: Could the renderer provide the device_id the
VideoCaptureManager wants? On the renderer-side, I imagine you'll be ultimately
calling into content::VideoCaptureImpl to request the photo be taken, right? The
needed device ID should be there.

This thought actually brings up another point: Perhaps there should not be an
ImageCapture mojo service to begin with? All the infrastructure you need for the
RPC to the browser process is available in VideoCaptureHost (browser-side) +
VideoCaptureImpl (renderer-side). Why not just add a new IPC message to do this?

+    const std::string& device_id) const {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  for (const LabeledDeviceRequest& device_request : requests_) {
+    for (const StreamDeviceInfo& info : device_request.second->devices) {
+      if (info.device.id == device_id) {
+        DCHECK_EQ(MEDIA_DEVICE_VIDEO_CAPTURE, info.device.type);
+        return info.session_id;
+      }
+    }
+  }
+  return StreamDeviceInfo::kNoId;
+}
+
 void MediaStreamManager::StopDevice(MediaStreamType type, int session_id) {
   DVLOG(1) << "StopDevice"
            << "{type = " << type << "}"