Added video capture capabilities retrieval and caching to VideoCaptureManager

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 6f0b0ec4702dedd2e9e2f43caecee942542ec5e8..e4591c0264e882d191136a85b729a64f9b6e07ef 100644
--- a/content/browser/renderer_host/media/video_capture_manager.h
+++ b/content/browser/renderer_host/media/video_capture_manager.h
@@ -59,7 +59,8 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
   // Called by VideoCaptureHost to locate a capture device for |capture_params|,
   // adding the Host as a client of the device's controller if successful. The
   // value of |capture_params.session_id| controls which device is selected;
-  // this value should be a session id previously returned by Open().
+  // this value should be a session id previously returned by Open(). The device
+  // capabilities are reduced to |capture_params|.
   //
   // If the device is not already started (i.e., no other client is currently
   // capturing from this device), this call will cause a VideoCaptureController
@@ -82,6 +83,13 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
                             VideoCaptureControllerID client_id,
                             VideoCaptureControllerEventHandler* client_handler);
 
+  // Retrieve the available capture capabilities for a particular device. The
+  // capabilities are cached during device(s) enumeration and updated as clients
+  // open the device(s). This call is asynchronous but expected to return fast
+  // since the capabilities are cached; the reply will be received in
+  // listener_->DeviceCapabilitiesEnumerated().

[perkj_chrome, 2013/10/29 12:13:36]

This is not what we discussed. You want to access the capabilities from the
VideoCaptureHost as we talked about and as you wrote in your email. 
Also - since you have already cached the capabilities you should be able make
this syncronous.

The actual device is identified in the same way as when you start a capture
device, according to the comments in StartCaptureForClient it is
|capture_params.session_id|.

+  void EnumerateDeviceCapabilities(const StreamDeviceInfo& device_info);
+
  private:
   virtual ~VideoCaptureManager();
   struct DeviceEntry;
@@ -96,6 +104,9 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
   void OnClosed(MediaStreamType type, int capture_session_id);
   void OnDevicesEnumerated(MediaStreamType stream_type,
                            const media::VideoCaptureDevice::Names& names);
+  void OnDeviceCapabilitiesEnumerated(
+      const StreamDeviceInfo& device_info,
+      const media::VideoCaptureCapabilities& capabilities);
 
   // Find a DeviceEntry by its device ID and type, if it is already opened.
   DeviceEntry* GetDeviceEntryForMediaStreamDevice(
@@ -115,6 +126,10 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
   media::VideoCaptureDevice::Names GetAvailableDevicesOnDeviceThread(
       MediaStreamType stream_type);
 
+  // Queries and returns the video capture capabilities of a device.
+  media::VideoCaptureCapabilities GetDeviceCapabilitiesOnDeviceThread(
+      const StreamDeviceInfo& device_info);
+
   // Create and Start a new VideoCaptureDevice, storing the result in
   // |entry->video_capture_device|. Ownership of |client| passes to
   // the device.
@@ -171,11 +186,26 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
   // default. This is only used for the MEDIA_DEVICE_VIDEO_CAPTURE device type.
   bool use_fake_device_;
 
-  // We cache the enumerated video capture devices in
-  // GetAvailableDevicesOnDeviceThread() and then later look up the requested ID
-  // when a device is created in DoStartDeviceOnDeviceThread(). Used only on the
-  // device thread.
-  media::VideoCaptureDevice::Names video_capture_devices_;
+  // This class is a convenient wrap of a devices' name and associated video
+  // capture capabilities.
+  class DeviceInfo {

[miu, 2013/10/29 18:43:27]

C++ style: struct, not class

+   public:
+    DeviceInfo();
+    DeviceInfo(const media::VideoCaptureDevice::Name& name,
+               const media::VideoCaptureCapabilities& capabilities);
+    ~DeviceInfo();
+
+    media::VideoCaptureDevice::Name name_;
+    media::VideoCaptureCapabilities capabilities_;
+  };
+  // Local cache of the enumerated video capture devices' names and capture
+  // capabilities. This cache is created in GetAvailableDevicesOnDeviceThread()
+  // and used via requested ID lookup when a device is created in
+  // DoStartDeviceOnDeviceThread(). The cache is only used in device thread.
+  // The capabilities are retrieved via EnumerateDeviceCapabilities().
+  std::vector<class DeviceInfo> devices_info_cache_;

[miu, 2013/10/29 18:43:27]

remove "class "

[miu, 2013/10/29 18:43:27]

Consider making this a vector<DeviceInfo*> instead, to avoid unnecessary copying
of the struct.

[tommi (sloooow) - chröme, 2013/10/29 20:26:24]

+1.
base::ScopedVector could come in handy:
https://code.google.com/p/chromium/codesearch#chromium/src/base/memory/scoped...

+  class DeviceInfo* FindDeviceInfoById(const std::string& id);

[miu, 2013/10/29 18:43:27]

remove "class "

[miu, 2013/10/29 18:43:27]

C++ style: Move this method up (before data members).

+
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureManager);
 };