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

This is a reland of f51b93d7

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}

Bug: 1095764
Bug: b/159154368
Change-Id: Ib3fbf021e10e48b3cb7289427ed130b01109a71d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388153Reviewed-by: Yuri Wiitala <miu@chromium.org>
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Auto-Submit: John Williams <jrw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804019}

chrome/browser/media/cast_mirroring_service_host_browsertest.cc

@@ -20,6 +20,7 @@
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/test/browser_test.h"
+#include "content/public/test/test_utils.h"
 #include "media/capture/mojom/video_capture.mojom.h"
 #include "media/capture/mojom/video_capture_types.mojom.h"
 #include "media/capture/video_capture_types.h"
@@ -182,6 +183,22 @@ class CastMirroringServiceHostBrowserTest
     host_.reset();
   }
 
+  void CloseWebContents() {
+    TabStripModel* const tab_strip = browser()->tab_strip_model();
+    content::WebContents* const web_contents =
+        tab_strip->GetActiveWebContents();
+    content::WebContentsDestroyedWatcher watcher(web_contents);
+
+    // 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);
+
+    watcher.Wait();
+  }
+
   void RequestRefreshFrame() {
     base::RunLoop run_loop;
     EXPECT_CALL(*video_frame_receiver_, OnBufferReadyCall(_))
@@ -255,6 +272,11 @@ 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

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

components/mirroring/service/mirroring_service.h

@@ -33,6 +33,8 @@ 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.