Revert "[Cast MRP] Stop mirroring immediately when a the tab is closed."

This reverts commit f51b93d7.

Reason for revert: Suspecting as cause of crbug.com/1123786.

Original change's description:
> [Cast MRP] Stop mirroring immediately when a the tab is closed.
> 
> Bug: 1095764, b/159154368
> Change-Id: I36829467e3a6477499c76ae0b15e110acba00c89
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2346911
> Reviewed-by: Yuri Wiitala <miu@chromium.org>
> Commit-Queue: John Williams <jrw@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#803343}

TBR=miu@chromium.org,dominickn@chromium.org,jrw@chromium.org

Change-Id: I3c8e562ee39e8cbf7ef5a5bb0312c9d51da7acc3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1095764
Bug: b/159154368
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2386439Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803377}

chrome/browser/media/cast_mirroring_service_host_browsertest.cc

@@ -182,18 +182,6 @@ class CastMirroringServiceHostBrowserTest
     host_.reset();
   }
 
-  void CloseWebContents() {
-    TabStripModel* const tab_strip = browser()->tab_strip_model();
-    content::WebContents* const web_contents =
-        tab_strip->GetActiveWebContents();
-    // Add a new tab so the browser doesn't close.
-    AddBlankTabAndShow(browser());
-    EXPECT_CALL(*this, DidStop()).Times(1);
-    tab_strip->CloseWebContentsAt(
-        tab_strip->GetIndexOfWebContents(web_contents),
-        TabStripModel::CLOSE_CREATE_HISTORICAL_TAB);
-  }
-
   void RequestRefreshFrame() {
     base::RunLoop run_loop;
     EXPECT_CALL(*video_frame_receiver_, OnBufferReadyCall(_))
@@ -267,11 +255,6 @@ IN_PROC_BROWSER_TEST_F(CastMirroringServiceHostBrowserTest, CaptureTabAudio) {
   StopMirroring();
 }
 
-IN_PROC_BROWSER_TEST_F(CastMirroringServiceHostBrowserTest, TabClosed) {
-  StartTabMirroring();
-  CloseWebContents();
-}
-
 IN_PROC_BROWSER_TEST_F(CastMirroringServiceHostBrowserTest, TabIndicator) {
   content::WebContents* const contents =
       browser()->tab_strip_model()->GetActiveWebContents();

components/mirroring/service/mirroring_service.cc

@@ -15,10 +15,7 @@ MirroringService::MirroringService(
     mojo::PendingReceiver<mojom::MirroringService> receiver,
     scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
     : receiver_(this, std::move(receiver)),
-      io_task_runner_(std::move(io_task_runner)) {
-  receiver_.set_disconnect_handler(
-      base::BindOnce(&MirroringService::OnDisconnect, base::Unretained(this)));
-}
+      io_task_runner_(std::move(io_task_runner)) {}
 
 MirroringService::~MirroringService() = default;
 
@@ -36,8 +33,4 @@ void MirroringService::Start(
       std::move(inbound_channel), io_task_runner_);
 }
 
-void MirroringService::OnDisconnect() {
-  session_.reset();
-}
-
 }  // namespace mirroring

components/mirroring/service/mirroring_service.h

@@ -33,8 +33,6 @@ class COMPONENT_EXPORT(MIRRORING_SERVICE) MirroringService final
              mojo::PendingReceiver<mojom::CastMessageChannel> inbound_channel)
       override;
 
-  void OnDisconnect();
-
   mojo::Receiver<mojom::MirroringService> receiver_;
   const scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
   std::unique_ptr<Session> session_;  // Current mirroring session.