camera: Use queue for pending photo options callbacks

When there are multiple requests for setting photo options callbacks,
pushing the callbacks into a queue instead of storing the latest one only.

Bug: 1142931
Test: https://1142931.glitch.me/?timeout=100
Change-Id: Ia4feac88de5600b696cf05f31fd0cea7c2612223
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2513809Reviewed-by: Shik Chen <shik@chromium.org>
Commit-Queue: Wei Lee <wtlee@chromium.org>
Auto-Submit: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823937}

media/capture/video/chromeos/camera_device_delegate.cc

@@ -530,6 +530,11 @@ void CameraDeviceDelegate::SetPhotoOptions(
                                       static_cast<int32_t>(settings->width) ||
                                   current_blob_resolution_.height() !=
                                       static_cast<int32_t>(settings->height));
+  // If there is callback of SetPhotoOptions(), the streams might being
+  // reconfigured and we should notify them once the reconfiguration is done.
+  if (!pending_set_photo_option_callbacks_.empty()) {
+    pending_set_photo_option_callbacks_.push(std::move(callback));
+  } else {
     if (!request_manager_->HasStreamsConfiguredForTakePhoto() ||
         should_reconfigure_streams) {
       if (is_resolution_specified) {
@@ -542,11 +547,11 @@ void CameraDeviceDelegate::SetPhotoOptions(
         request_manager_->StopPreview(base::BindOnce(
             &CameraDeviceDelegate::OnFlushed, GetWeakPtr(), base::nullopt));
       }
-    set_photo_option_callback_ = std::move(callback);
+      pending_set_photo_option_callbacks_.push(std::move(callback));
     } else {
-    set_photo_option_callback_.Reset();
       std::move(callback).Run(true);
     }
+  }
   result_metadata_frame_number_for_photo_state_ = current_request_frame_number_;
 }
 
@@ -1082,8 +1087,9 @@ void CameraDeviceDelegate::OnGotFpsRange(
     TakePhotoImpl();
   }
 
-  if (set_photo_option_callback_) {
-    std::move(set_photo_option_callback_).Run(true);
+  while (!pending_set_photo_option_callbacks_.empty()) {
+    std::move(pending_set_photo_option_callbacks_.front()).Run(true);
+    pending_set_photo_option_callbacks_.pop();
   }
 }
 

media/capture/video/chromeos/camera_device_delegate.h

@@ -6,6 +6,7 @@
 #define MEDIA_CAPTURE_VIDEO_CHROMEOS_CAMERA_DEVICE_DELEGATE_H_
 
 #include <memory>
+#include <queue>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
@@ -238,7 +239,8 @@ class CAPTURE_EXPORT CameraDeviceDelegate final
 
   base::OnceClosure device_close_callback_;
 
-  VideoCaptureDevice::SetPhotoOptionsCallback set_photo_option_callback_;
+  std::queue<VideoCaptureDevice::SetPhotoOptionsCallback>
+      pending_set_photo_option_callbacks_;
 
   CameraAppDeviceImpl* camera_app_device_;  // Weak.