ImageCapture: queue requests if device is not started (Linux,CrOs)

media/capture/video/linux/video_capture_device_linux.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 "media/capture/video/linux/video_capture_device_linux.h"
 
 #include <stddef.h>
 
 #include <list>
 
@@ skipping 51 matching lines @@
   if (!capture_impl_) {
     client->OnError(FROM_HERE, "Failed to create VideoCaptureDelegate");
     return;
   }
   v4l2_thread_.task_runner()->PostTask(
       FROM_HERE,
       base::Bind(&V4L2CaptureDelegate::AllocateAndStart, capture_impl_,
                  params.requested_format.frame_size.width(),
                  params.requested_format.frame_size.height(),
                  params.requested_format.frame_rate, base::Passed(&client)));
+
+  for (const auto& request : photo_requests_queue_)
+    v4l2_thread_.task_runner()->PostTask(FROM_HERE, request);
+  photo_requests_queue_.clear();
 }
 
 void VideoCaptureDeviceLinux::StopAndDeAllocate() {
   if (!v4l2_thread_.IsRunning())
     return;  // Wrong state.
   v4l2_thread_.task_runner()->PostTask(
       FROM_HERE,
       base::Bind(&V4L2CaptureDelegate::StopAndDeAllocate, capture_impl_));
   v4l2_thread_.Stop();
 
   capture_impl_ = nullptr;
 }
 
 void VideoCaptureDeviceLinux::TakePhoto(TakePhotoCallback callback) {
   DCHECK(capture_impl_);
-  if (!v4l2_thread_.IsRunning())
+  auto functor = base::Bind(&V4L2CaptureDelegate::TakePhoto, capture_impl_,

[xianglu, 2016/12/06 18:18:03]

s/functor/callback/ ?

[mcasas, 2016/12/06 19:21:03]

Yeah, but |callback| is a parameter... couldn't come up with an 
alternative name TBH.

+                            base::Passed(&callback));
+  if (!v4l2_thread_.IsRunning()) {
+    // We have to wait until we get the device AllocateAndStart()ed.
+    photo_requests_queue_.push_back(std::move(functor));
     return;
-  v4l2_thread_.task_runner()->PostTask(
-      FROM_HERE, base::Bind(&V4L2CaptureDelegate::TakePhoto, capture_impl_,
-                            base::Passed(&callback)));
+  }
+  v4l2_thread_.task_runner()->PostTask(FROM_HERE, std::move(functor));
 }
 
 void VideoCaptureDeviceLinux::GetPhotoCapabilities(
     GetPhotoCapabilitiesCallback callback) {
-  if (!v4l2_thread_.IsRunning())
-    return;  // Wrong state.
-  v4l2_thread_.task_runner()->PostTask(
-      FROM_HERE, base::Bind(&V4L2CaptureDelegate::GetPhotoCapabilities,
-                            capture_impl_, base::Passed(&callback)));
+  auto functor = base::Bind(&V4L2CaptureDelegate::GetPhotoCapabilities,
+                            capture_impl_, base::Passed(&callback));
+  if (!v4l2_thread_.IsRunning()) {
+    // We have to wait until we get the device AllocateAndStart()ed.
+    photo_requests_queue_.push_back(std::move(functor));
+    return;
+  }
+  v4l2_thread_.task_runner()->PostTask(FROM_HERE, std::move(functor));
 }
 
 void VideoCaptureDeviceLinux::SetPhotoOptions(
     mojom::PhotoSettingsPtr settings,
     SetPhotoOptionsCallback callback) {
-  if (!v4l2_thread_.IsRunning())
-    return;  // Wrong state.
-  v4l2_thread_.task_runner()->PostTask(
-      FROM_HERE,
+  auto functor =
       base::Bind(&V4L2CaptureDelegate::SetPhotoOptions, capture_impl_,
-                 base::Passed(&settings), base::Passed(&callback)));
+                 base::Passed(&settings), base::Passed(&callback));
+  if (!v4l2_thread_.IsRunning()) {
+    // We have to wait until we get the device AllocateAndStart()ed.
+    photo_requests_queue_.push_back(std::move(functor));
+    return;
+  }
+  v4l2_thread_.task_runner()->PostTask(FROM_HERE, std::move(functor));
 }
 
 void VideoCaptureDeviceLinux::SetRotation(int rotation) {
   if (v4l2_thread_.IsRunning()) {
     v4l2_thread_.task_runner()->PostTask(
         FROM_HERE,
         base::Bind(&V4L2CaptureDelegate::SetRotation, capture_impl_, rotation));
   }
 }
 
 // static
 int VideoCaptureDeviceLinux::TranslatePowerLineFrequencyToV4L2(
     PowerLineFrequency frequency) {
   switch (frequency) {
     case media::PowerLineFrequency::FREQUENCY_50HZ:
       return V4L2_CID_POWER_LINE_FREQUENCY_50HZ;
     case media::PowerLineFrequency::FREQUENCY_60HZ:
       return V4L2_CID_POWER_LINE_FREQUENCY_60HZ;
     default:
       // If we have no idea of the frequency, at least try and set it to AUTO.
       return V4L2_CID_POWER_LINE_FREQUENCY_AUTO;
   }
 }
 
 }  // namespace media