Make UserMediaClient::Request heap allocated

... instead of stack allocated.

This is a precusor CL for making use of ApplyConstraintsRequest directly
in user_media_client.cc|h and apply_constraints_processor.cc|h, instead
of its Blink-exposed wrapper class, WebApplyConstraintsRequest.

This is needed because ApplyConstraintsRequest is GC-ed by OilPan, so
being UserMediaClient::Request the class that will own it, it needs to be
(Oilpan) heap allocated.

In a follow up step [1], it was changed to on-Oilpan-heap allocation.

[1] https://crrev.com/c/1768778

BUG=704136
R=guidou@chromium.org, haraken@chromium.org

Change-Id: I7b3965d892f99a93d12d65ffee3140f08caafbd1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1768789
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Auto-Submit: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#690313}

third_party/blink/renderer/modules/mediastream/user_media_client.cc

@@ -187,7 +187,8 @@ void UserMediaClient::RequestUserMedia(
   std::unique_ptr<UserMediaRequestInfo> request_info =
       std::make_unique<UserMediaRequestInfo>(request_id, web_request,
                                              user_gesture);
-  pending_request_infos_.push_back(Request(std::move(request_info)));
+  pending_request_infos_.push_back(
+      std::make_unique<Request>(std::move(request_info)));
   if (!is_processing_request_)
     MaybeProcessNextRequestInfo();
 }
@@ -196,13 +197,13 @@ void UserMediaClient::ApplyConstraints(
     const blink::WebApplyConstraintsRequest& web_request) {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
 
-  pending_request_infos_.push_back(Request(web_request));
+  pending_request_infos_.push_back(std::make_unique<Request>(web_request));
   if (!is_processing_request_)
     MaybeProcessNextRequestInfo();
 }
 
 void UserMediaClient::StopTrack(const blink::WebMediaStreamTrack& web_track) {
-  pending_request_infos_.push_back(Request(web_track));
+  pending_request_infos_.push_back(std::make_unique<Request>(web_track));
   if (!is_processing_request_)
     MaybeProcessNextRequestInfo();
 }
@@ -216,25 +217,25 @@ void UserMediaClient::MaybeProcessNextRequestInfo() {
   if (is_processing_request_ || pending_request_infos_.empty())
     return;
 
-  Request current_request = std::move(pending_request_infos_.front());
+  auto current_request = std::move(pending_request_infos_.front());
   pending_request_infos_.pop_front();
   is_processing_request_ = true;
 
-  if (current_request.IsUserMedia()) {
+  if (current_request->IsUserMedia()) {
     user_media_processor_->ProcessRequest(
-        current_request.MoveUserMediaRequest(),
+        current_request->MoveUserMediaRequest(),
         WTF::Bind(&UserMediaClient::CurrentRequestCompleted,
                   WrapWeakPersistent(this)));
-  } else if (current_request.IsApplyConstraints()) {
+  } else if (current_request->IsApplyConstraints()) {
     apply_constraints_processor_->ProcessRequest(
-        current_request.apply_constraints_request(),
+        current_request->apply_constraints_request(),
         WTF::Bind(&UserMediaClient::CurrentRequestCompleted,
                   WrapWeakPersistent(this)));
   } else {
-    DCHECK(current_request.IsStopTrack());
+    DCHECK(current_request->IsStopTrack());
     blink::WebPlatformMediaStreamTrack* track =
         blink::WebPlatformMediaStreamTrack::GetTrack(
-            current_request.web_track_to_stop());
+            current_request->web_track_to_stop());
     if (track) {
       track->StopAndNotify(WTF::Bind(&UserMediaClient::CurrentRequestCompleted,
                                      WrapWeakPersistent(this)));
@@ -273,8 +274,8 @@ void UserMediaClient::CancelUserMediaRequest(
   } else {
     for (auto it = pending_request_infos_.begin();
          it != pending_request_infos_.end(); ++it) {
-      if (it->IsUserMedia() &&
-          it->user_media_request()->web_request == web_request) {
+      if ((*it)->IsUserMedia() &&
+          (*it)->user_media_request()->web_request == web_request) {
         pending_request_infos_.erase(it);
         did_remove_request = true;
         break;

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

@@ -91,6 +91,8 @@ class MODULES_EXPORT UserMediaClient
     std::unique_ptr<UserMediaRequestInfo> user_media_request_;
     blink::WebApplyConstraintsRequest apply_constraints_request_;
     blink::WebMediaStreamTrack web_track_to_stop_;
+
+    DISALLOW_COPY_AND_ASSIGN(Request);
   };
 
   void MaybeProcessNextRequestInfo();
@@ -119,7 +121,7 @@ class MODULES_EXPORT UserMediaClient
   // and |pending_request_infos_| is a list of queued requests.
   bool is_processing_request_ = false;
 
-  Deque<Request> pending_request_infos_;
+  Deque<std::unique_ptr<Request>> pending_request_infos_;
 
   THREAD_CHECKER(thread_checker_);