Implement device enumeration for PPB_VideoCapture_Dev.

ppapi/api/dev/ppb_video_capture_dev.idl

Index: ppapi/api/dev/ppb_video_capture_dev.idl
diff --git a/ppapi/api/dev/ppb_video_capture_dev.idl b/ppapi/api/dev/ppb_video_capture_dev.idl
index fd7919094ba69a667362e5424cc2628df3c3a1e9..fe118c23d00cce1991f826fe37710abdfd3397c0 100644
--- a/ppapi/api/dev/ppb_video_capture_dev.idl
+++ b/ppapi/api/dev/ppb_video_capture_dev.idl
@@ -7,7 +7,8 @@
  * This file defines the <code>PPB_VideoCapture_Dev</code> interface.
  */
 label Chrome {
-  M14 = 0.1
+  M14 = 0.1,
+  M18 = 0.2
 };
 
 /**
@@ -52,7 +53,7 @@ interface PPB_VideoCapture_Dev {
    * Starts the capture. |requested_info| is a pointer to a structure containing
    * the requested resolution and frame rate. |buffer_count| is the number of
    * buffers requested by the plugin. Note: it is only used as advisory, the
-   * browser may allocate more of fewer based on available resources.
+   * browser may allocate more or fewer based on available resources.
    * How many buffers depends on usage. At least 2 to make sure latency doesn't
    * cause lost frames. If the plugin expects to hold on to more than one buffer
    * at a time (e.g. to do multi-frame processing, like video encoding), it
@@ -67,6 +68,46 @@ interface PPB_VideoCapture_Dev {
       [in] uint32_t buffer_count);
 
   /**
+   * Enumerates video capture devices. Once the operation is completed
+   * successfully. |GetDevices()| can be used to retrieve the devices.
+   */
+  [version=0.2]
+  int32_t EnumerateDevices(
+      [in] PP_Resource video_capture,
+      [in] PP_CompletionCallback callback);
+
+  /**
+   * Gets video capture devices. The returned value is a PPB_ResourceArray_Dev
+   * resource if successful, which holds a list of PPB_DeviceRef_Dev resources.
+   */
+  [version=0.2]
+  PP_Resource GetDevices(
+      [in] PP_Resource video_capture);
+
+  /**
+   * Starts the capture. |device_ref| identifies a video capture device. It
+   * could be one of the resource in the array returned by |GetDevices()|, or 0
+   * which means the default device.
+   * |requested_info| is a pointer to a structure containing the requested
+   * resolution and frame rate. |buffer_count| is the number of buffers
+   * requested by the plugin. Note: it is only used as advisory, the browser may
+   * allocate more or fewer based on available resources. How many buffers
+   * depends on usage. At least 2 to make sure latency doesn't cause lost
+   * frames. If the plugin expects to hold on to more than one buffer at a time
+   * (e.g. to do multi-frame processing, like video encoding), it should request
+   * that many more.
+   *
+   * Returns PP_ERROR_FAILED if called when the capture was already started, or
+   * PP_OK on success.
+   */
+  [version=0.2]
+  int32_t StartCapture(
+      [in] PP_Resource video_capture,
+      [in] PP_Resource device_ref,
+      [in] PP_VideoCaptureDeviceInfo_Dev requested_info,
+      [in] uint32_t buffer_count);
+
+  /**
    * Allows the browser to reuse a buffer that was previously sent by
    * PPP_VideoCapture_Dev.OnBufferReady. |buffer| is the index of the buffer in
    * the array returned by PPP_VideoCapture_Dev.OnDeviceInfo.