Use WTF::Deque instead of std::list in user_media_client_impl.h

The associated TODO says to replace the use of std::list in this file
by a WTF::HashSet. However, after looking at how the container is
actually used in the .cc file, WTF::Deque seems like a perfect match.

BUG=704136
R=guidou@chromium.org

Change-Id: I731a3770c7039fcfd1520caf1277c52ffefc94d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1744048Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#685190}

third_party/blink/renderer/modules/mediastream/user_media_client_impl.h

@@ -5,7 +5,6 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASTREAM_USER_MEDIA_CLIENT_IMPL_H_
 #define THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASTREAM_USER_MEDIA_CLIENT_IMPL_H_
 
-#include <list>
 #include <memory>
 
 #include "base/macros.h"
@@ -21,6 +20,7 @@
 #include "third_party/blink/renderer/core/execution_context/context_lifecycle_observer.h"
 #include "third_party/blink/renderer/modules/mediastream/user_media_processor.h"
 #include "third_party/blink/renderer/modules/modules_export.h"
+#include "third_party/blink/renderer/platform/wtf/deque.h"
 
 namespace blink {
 
@@ -126,8 +126,7 @@ class MODULES_EXPORT UserMediaClientImpl : public blink::WebUserMediaClient {
   // and |pending_request_infos_| is a list of queued requests.
   bool is_processing_request_ = false;
 
-  // TODO(crbug.com/704136): Use WTF::HashSet.
-  std::list<Request> pending_request_infos_;
+  Deque<Request> pending_request_infos_;
 
   SEQUENCE_CHECKER(sequence_checker_);