Add still image capture interface for VideoCaptureDevice.

media/video/capture/video_capture_device.h

Index: media/video/capture/video_capture_device.h
diff --git a/media/video/capture/video_capture_device.h b/media/video/capture/video_capture_device.h
index 382dad6cdc461d7d6d20bf04ab8e7e91693ae503..d849155952f6d778fda6b732b3e039de41471f13 100644
--- a/media/video/capture/video_capture_device.h
+++ b/media/video/capture/video_capture_device.h
@@ -216,6 +216,41 @@ class MEDIA_EXPORT VideoCaptureDevice {
 
     // VideoCaptureDevice requests the |message| to be logged.
     virtual void OnLog(const std::string& message) {}
+
+    // The video stream has been muted. After this callback, no more
+    // OnIncomingCapturedData() will be called. This may happen when
+    // CaptureImage() has called. After the still image captured, the client
+    // will get notified by OnUnmute() and the video stream will be resumed.
+    virtual void OnMute() {}
+
+    // The video stream has resumed.
+    virtual void OnUnmute() {}
+  };
+
+  // Interface for clients that use VideoCaptureDevice for taking still images.
+  class MEDIA_EXPORT ImageClient {
+   public:
+    virtual ~ImageClient() {}
+
+    // Callback function to notify the client a captured image is available.
+    //
+    // The captured still image is stored at address |data| and is of |length|
+    // bytes. The format of the frame is described by |format|, and is assumed
+    // to be tightly packed. The still image should be rotated |rotation|
+    // degrees clockwise for viewing.
+    //
+    // Note that the content in |data| will not be valid after this callback
+    // returns. Copy the content to use it later.
+    virtual void OnIncomingCapturedData(const uint8* data,
+                                        int length,
+                                        const ImageCaptureFormat& format,
+                                        int rotation,
+                                        base::TimeTicks timestamp) = 0;
+
+    // Callback function to notify the client about a failure of the image
+    // capture. The VideoCaptureDevice must be StopAndDeAllocate()-ed.
+    // |reason| contains a text description of the error.
+    virtual void OnError(const std::string& reason) = 0;
   };
 
   // Creates a VideoCaptureDevice object.
@@ -228,13 +263,20 @@ class MEDIA_EXPORT VideoCaptureDevice {
   // Gets the names of all video capture devices connected to this computer.
   static void GetDeviceNames(Names* device_names);
 
-  // Gets the supported formats of a particular device attached to the system.
+  // Gets formats for still image capture supported by a particular |device|
+  // attached to the system.
   // This method should be called before allocating or starting a device. In

[Pawel Osciak, 2014/09/29 00:13:37]

What will happen if it's called at a wrong time (in terms of API), error,
callback, etc.?

   // case format enumeration is not supported, or there was a problem, the
   // formats array will be empty.
   static void GetDeviceSupportedFormats(const Name& device,
                                         VideoCaptureFormats* supported_formats);
 
+  // Gets the supported formats for still image of a particular device attached
+  // to the system.
+  static void GetDeviceSupportedImageFormats(
+      const Name& device,
+      ImageCaptureFormats* supported_formats);
+
   // Prepares the camera for use. After this function has been called no other
   // applications can use the camera. StopAndDeAllocate() must be called before
   // the object is deleted.
@@ -258,6 +300,30 @@ class MEDIA_EXPORT VideoCaptureDevice {
   // defined, otherwise returns 0.
   int GetPowerLineFrequencyForLocation() const;
 
+  // Initializes the device for still image capture for the given image format.
+  //
+  // This function must be called between AllocateAndStart() and
+  // StopAndDeAllocate().
+  virtual void InitializeImageCapture(const ImageCaptureFormat& image_format,
+                                      scoped_ptr<ImageClient> client) {}
+
+  // Releases resources for image capture.
+  //
+  // The ImageClient passed from InitializeImageCapture will be freed. This
+  // method must be called between InitializeImageCapture() and
+  // StopAndDeAllocate().
+  virtual void ReleaseImageCapture() {}
+
+  // Gets one image from the device asynchronously.
+  //
+  // The image will be returned via the ImageClient::OnIncomingCapturedData()
+  // callback. If the video stream has to be stopped to capture the still image,
+  // the Client::OnMute() and Client::OnUnmute() will be called.
+  //
+  // This function must be called between InitializeImageCapture() and
+  // ReleaseImageCapture().
+  virtual void CaptureImage() {}
+
  protected:
   static const int kPowerLine50Hz = 50;
   static const int kPowerLine60Hz = 60;