Reland "Lazily create UserMediaController"

This is a reland of [1], originally revert in [2], being
suspicious of have caused [3].

The bug was fixed differently [4], and it should be safe to reland
this CL.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1760407
[2] https://chromium-review.googlesource.com/c/chromium/src/+/1758468
[3] https://crbug.com/995709
[4] https://chromium-review.googlesource.com/c/chromium/src/+/1758471

Original commit message:

  This CL addressed guidou's remark on [1], that
  was accidentally left off when splitting the CL into
  smaller pieces.

  [1] https://crrev.com/c/1757490/4/third_party/blink/renderer/modules/modules_initializer.cc#185

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

Change-Id: I76477b2adfbf4f6b942b066640b4e2d19a7e8e42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1765489Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Auto-Submit: Antonio Gomes <tonikitoo@igalia.com>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689463}

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

@@ -29,11 +29,9 @@ namespace blink {
 
 const char UserMediaController::kSupplementName[] = "UserMediaController";
 
-UserMediaController::UserMediaController(LocalFrame& frame,
-                                         UserMediaClient* client)
+UserMediaController::UserMediaController(LocalFrame& frame)
     : Supplement<LocalFrame>(frame),
-      ContextLifecycleObserver(frame.GetDocument()),
-      client_(client) {}
+      ContextLifecycleObserver(frame.GetDocument()) {}
 
 void UserMediaController::Trace(blink::Visitor* visitor) {
   Supplement<LocalFrame>::Trace(visitor);
@@ -41,13 +39,24 @@ void UserMediaController::Trace(blink::Visitor* visitor) {
   visitor->Trace(client_);
 }
 
+UserMediaClient* UserMediaController::Client() {
+  if (!client_) {
+    client_ = MakeGarbageCollected<UserMediaClient>(
+        GetFrame(), GetFrame()->GetTaskRunner(TaskType::kInternalMedia));
+  }
+
+  return client_;
+}
+
 void UserMediaController::ContextDestroyed(ExecutionContext*) {
+  if (!client_)
+    return;
   client_->ContextDestroyed();
 }
 
-void ProvideUserMediaTo(LocalFrame& frame, UserMediaClient* client) {
+void ProvideUserMediaTo(LocalFrame& frame) {
   UserMediaController::ProvideTo(
-      frame, MakeGarbageCollected<UserMediaController>(frame, client));
+      frame, MakeGarbageCollected<UserMediaController>(frame));
 }
 
 }  // namespace blink

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

@@ -46,10 +46,10 @@ class UserMediaController final
  public:
   static const char kSupplementName[];
 
-  UserMediaController(LocalFrame&, UserMediaClient*);
+  UserMediaController(LocalFrame&);
   void Trace(blink::Visitor*) override;
 
-  UserMediaClient* Client() const { return client_; }
+  UserMediaClient* Client();
 
   void RequestUserMedia(UserMediaRequest*);
   void CancelUserMediaRequest(UserMediaRequest*);
@@ -70,29 +70,29 @@ class UserMediaController final
 };
 
 inline void UserMediaController::RequestUserMedia(UserMediaRequest* request) {
-  client_->RequestUserMedia(request);
+  Client()->RequestUserMedia(request);
   has_requested_user_media_ = true;
 }
 
 inline void UserMediaController::CancelUserMediaRequest(
     UserMediaRequest* request) {
-  client_->CancelUserMediaRequest(WebUserMediaRequest(request));
+  Client()->CancelUserMediaRequest(WebUserMediaRequest(request));
 }
 
 inline void UserMediaController::ApplyConstraints(
     ApplyConstraintsRequest* request) {
-  client_->ApplyConstraints(WebApplyConstraintsRequest(request));
+  Client()->ApplyConstraints(WebApplyConstraintsRequest(request));
 }
 
 inline void UserMediaController::StopTrack(MediaStreamComponent* track) {
-  client_->StopTrack(WebMediaStreamTrack(track));
+  Client()->StopTrack(WebMediaStreamTrack(track));
 }
 
 inline bool UserMediaController::HasRequestedUserMedia() {
   return has_requested_user_media_;
 }
 
-MODULES_EXPORT void ProvideUserMediaTo(LocalFrame&, UserMediaClient*);
+MODULES_EXPORT void ProvideUserMediaTo(LocalFrame&);
 
 }  // namespace blink
 

third_party/blink/renderer/modules/modules_initializer.cc

@@ -181,9 +181,7 @@ void ModulesInitializer::InstallSupplements(LocalFrame& frame) const {
   DCHECK(client);
   ProvidePushMessagingClientTo(
       frame, MakeGarbageCollected<PushMessagingClient>(frame));
-  ProvideUserMediaTo(
-      frame, MakeGarbageCollected<UserMediaClient>(
-                 &frame, frame.GetTaskRunner(TaskType::kInternalMedia)));
+  ProvideUserMediaTo(frame);
   ProvideLocalFileSystemTo(frame, std::make_unique<LocalFileSystemClient>());
 
   ScreenOrientationControllerImpl::ProvideTo(frame);