VideoCaptureDeviceFactory: Change device enumeration to callback + QTKit enumerates in UI thread.

content/browser/renderer_host/media/video_capture_manager.cc

 // Copyright (c) 2012 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.
 
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 
 #include <set>
 
 #include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "content/browser/media/capture/web_contents_video_capture_device.h"
 #include "content/browser/renderer_host/media/video_capture_controller.h"
 #include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/desktop_media_id.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/media_stream_request.h"
+#include "media/base/bind_to_current_loop.h"
 #include "media/base/scoped_histogram_timer.h"
 #include "media/video/capture/video_capture_device.h"
 #include "media/video/capture/video_capture_device_factory.h"
 
 #if defined(ENABLE_SCREEN_CAPTURE)
 #include "content/browser/media/capture/desktop_capture_device.h"
 #if defined(USE_AURA)
 #include "content/browser/media/capture/desktop_capture_device_aura.h"
 #endif
 #endif
@@ skipping 83 matching lines @@
 
 void VideoCaptureManager::Unregister() {
   DCHECK(listener_);
   listener_ = NULL;
 }
 
 void VideoCaptureManager::EnumerateDevices(MediaStreamType stream_type) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(1) << "VideoCaptureManager::EnumerateDevices, type " << stream_type;
   DCHECK(listener_);
-  base::PostTaskAndReplyWithResult(
-      device_task_runner_, FROM_HERE,
-      base::Bind(&VideoCaptureManager::GetAvailableDevicesInfoOnDeviceThread,
-                 this, stream_type, devices_info_cache_),
-      base::Bind(&VideoCaptureManager::OnDevicesInfoEnumerated, this,
-                 stream_type));
+  DCHECK_EQ(stream_type, MEDIA_DEVICE_VIDEO_CAPTURE);
+
+  // Bind a callback to ConsolidateDevicesInfoOnDeviceThread() with an argument
+  // for another callback to OnDevicesInfoEnumerated() to be run in the current
+  // loop, i.e. IO loop. Pass a timer for UMA histogram collection.
+  base::Callback<void(scoped_ptr<media::VideoCaptureDevice::Names>)>
+      devices_enumerated_callback =
+          base::Bind(&VideoCaptureManager::ConsolidateDevicesInfoOnDeviceThread,
+                     this,
+                     media::BindToCurrentLoop(base::Bind(
+                         &VideoCaptureManager::OnDevicesInfoEnumerated,
+                         this,
+                         stream_type,
+                         base::Owned(new base::ElapsedTimer()))),
+                     stream_type,
+                     devices_info_cache_);
+  // OK to use base::Unretained() since we own the VCDFactory and |this| is
+  // bound in |devices_enumerated_callback|.
+  device_task_runner_->PostTask(FROM_HERE,
+      base::Bind(&media::VideoCaptureDeviceFactory::EnumerateDeviceNames,
+                 base::Unretained(video_capture_device_factory_.get()),
+                 devices_enumerated_callback));
 }
 
 int VideoCaptureManager::Open(const StreamDeviceInfo& device_info) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(listener_);
 
   // Generate a new id for the session being opened.
   const media::VideoCaptureSessionId capture_session_id =
       new_capture_session_id_++;
 
@@ skipping 52 matching lines @@
 
   scoped_ptr<media::VideoCaptureDevice> video_capture_device;
   switch (entry->stream_type) {
     case MEDIA_DEVICE_VIDEO_CAPTURE: {
       // We look up the device id from the renderer in our local enumeration
       // since the renderer does not have all the information that might be
       // held in the browser-side VideoCaptureDevice::Name structure.
       DeviceInfo* found = FindDeviceInfoById(entry->id, devices_info_cache_);
       if (found) {
         video_capture_device =
-            video_capture_device_factory_->Create(
-                BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI),
-                found->name);
+            video_capture_device_factory_->Create(found->name);
       }
       break;
     }
     case MEDIA_TAB_VIDEO_CAPTURE: {
       video_capture_device.reset(
           WebContentsVideoCaptureDevice::Create(entry->id));
       break;
     }
     case MEDIA_DESKTOP_VIDEO_CAPTURE: {
 #if defined(ENABLE_SCREEN_CAPTURE)
@@ skipping 209 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!listener_) {
     // Listener has been removed.
     return;
   }
   listener_->Closed(stream_type, capture_session_id);
 }
 
 void VideoCaptureManager::OnDevicesInfoEnumerated(
     MediaStreamType stream_type,
+    base::ElapsedTimer* timer,
     const DeviceInfos& new_devices_info_cache) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
+  UMA_HISTOGRAM_TIMES(
+      "Media.VideoCaptureManager.GetAvailableDevicesInfoOnDeviceThreadTime",
+      timer->Elapsed());
   if (!listener_) {
     // Listener has been removed.
     return;
   }
   devices_info_cache_ = new_devices_info_cache;
 
   // Walk the |devices_info_cache_| and transform from VCD::Name to
   // StreamDeviceInfo for return purposes.
   StreamDeviceInfoArray devices;
   for (DeviceInfos::const_iterator it = devices_info_cache_.begin();
        it != devices_info_cache_.end(); ++it) {
     devices.push_back(StreamDeviceInfo(
         stream_type, it->name.GetNameAndModel(), it->name.id()));
   }
   listener_->DevicesEnumerated(stream_type, devices);
 }
 
 bool VideoCaptureManager::IsOnDeviceThread() const {
   return device_task_runner_->BelongsToCurrentThread();
 }
 
-VideoCaptureManager::DeviceInfos
-VideoCaptureManager::GetAvailableDevicesInfoOnDeviceThread(
+void VideoCaptureManager::ConsolidateDevicesInfoOnDeviceThread(
+    base::Callback<void(const DeviceInfos&)> on_devices_enumerated_callback,
     MediaStreamType stream_type,
-    const DeviceInfos& old_device_info_cache) {
-  SCOPED_UMA_HISTOGRAM_TIMER(
-      "Media.VideoCaptureManager.GetAvailableDevicesInfoOnDeviceThreadTime");
+    const DeviceInfos& old_device_info_cache,
+    scoped_ptr<media::VideoCaptureDevice::Names> names_snapshot) {
   DCHECK(IsOnDeviceThread());
-  media::VideoCaptureDevice::Names names_snapshot;
-  switch (stream_type) {
-    case MEDIA_DEVICE_VIDEO_CAPTURE:
-      // Cache the latest enumeration of video capture devices.
-      // We'll refer to this list again in OnOpen to avoid having to
-      // enumerate the devices again.
-      video_capture_device_factory_->GetDeviceNames(&names_snapshot);
-      break;
-    case MEDIA_DESKTOP_VIDEO_CAPTURE:
-      // Do nothing.
-      break;
-    default:
-      NOTREACHED();
-      break;
-  }
-
   // Construct |new_devices_info_cache| with the cached devices that are still
   // present in the system, and remove their names from |names_snapshot|, so we
   // keep there the truly new devices.
   DeviceInfos new_devices_info_cache;
   for (DeviceInfos::const_iterator it_device_info =
            old_device_info_cache.begin();
        it_device_info != old_device_info_cache.end(); ++it_device_info) {
      for (media::VideoCaptureDevice::Names::iterator it =
-              names_snapshot.begin();
-          it != names_snapshot.end(); ++it) {
+         names_snapshot->begin();
+          it != names_snapshot->end(); ++it) {
       if (it_device_info->name.id() == it->id()) {
         new_devices_info_cache.push_back(*it_device_info);
-        names_snapshot.erase(it);
+        names_snapshot->erase(it);
         break;
       }
     }
   }
 
   // Get the supported capture formats for the new devices in |names_snapshot|.
   for (media::VideoCaptureDevice::Names::const_iterator it =
-           names_snapshot.begin();
-       it != names_snapshot.end(); ++it) {
+      names_snapshot->begin();
+       it != names_snapshot->end(); ++it) {
     media::VideoCaptureFormats supported_formats;
     DeviceInfo device_info(*it, media::VideoCaptureFormats());
     video_capture_device_factory_->GetDeviceSupportedFormats(
         *it, &(device_info.supported_formats));
     ConsolidateCaptureFormats(&device_info.supported_formats);
     new_devices_info_cache.push_back(device_info);
   }
-  return new_devices_info_cache;
+
+  on_devices_enumerated_callback.Run(new_devices_info_cache);
 }
 
 VideoCaptureManager::DeviceEntry*
 VideoCaptureManager::GetDeviceEntryForMediaStreamDevice(
     const MediaStreamDevice& device_info) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   for (DeviceEntries::iterator it = devices_.begin();
        it != devices_.end(); ++it) {
     DeviceEntry* device = *it;
@@ skipping 92 matching lines @@
 void VideoCaptureManager::SaveDesktopCaptureWindowIdOnDeviceThread(
     media::VideoCaptureSessionId session_id,
     gfx::NativeViewId window_id) {
   DCHECK(IsOnDeviceThread());
   DCHECK(notification_window_ids_.find(session_id) ==
          notification_window_ids_.end());
   notification_window_ids_[session_id] = window_id;
 }
 
 }  // namespace content