From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jeremy Rose <japthorp@slack-corp.com>
Date: Tue, 12 Jul 2022 16:51:43 -0700
Subject: short-circuit permissions checks in MediaStreamDevicesController

The //components/permissions architecture is complicated and not that
widely used in Chromium, and mostly oriented around showing permissions
UI and/or remembering per-site permissions, which we're not interested
in.

Since we do a permissions check prior to invoking the
MediaStreamDevicesController, and don't (yet) provide the ability to set
granular permissions (e.g. allow video but not audio), just
short-circuit all the permissions checks in MSDC for now to allow us to
unduplicate this code.

diff --git a/components/webrtc/media_stream_devices_controller.cc b/components/webrtc/media_stream_devices_controller.cc
index efbea8c15b096344b0cc65cc337a9cdbd727cb55..ca31bba7fc6daf68e6862554a70032dfdc8285b5 100644
--- a/components/webrtc/media_stream_devices_controller.cc
+++ b/components/webrtc/media_stream_devices_controller.cc
@@ -57,7 +57,8 @@ bool PermissionIsRequested(blink::PermissionType permission,
 void MediaStreamDevicesController::RequestPermissions(
     const content::MediaStreamRequest& request,
     MediaStreamDeviceEnumerator* enumerator,
-    ResultCallback callback) {
+    ResultCallback callback,
+    bool previously_approved) {
   content::RenderFrameHost* rfh = content::RenderFrameHost::FromID(
       request.render_process_id, request.render_frame_id);
   // The RFH may have been destroyed by the time the request is processed.
@@ -93,6 +94,7 @@ void MediaStreamDevicesController::RequestPermissions(
 
   std::vector<blink::PermissionType> permission_types;
 
+#if 0
   content::PermissionController* permission_controller =
       web_contents->GetBrowserContext()->GetPermissionController();
 
@@ -153,19 +155,25 @@ void MediaStreamDevicesController::RequestPermissions(
       permission_types.push_back(blink::PermissionType::CAMERA_PAN_TILT_ZOOM);
     }
   }
+#endif
 
   // It is OK to ignore `request.security_origin` because it will be calculated
   // from `render_frame_host` and we always ignore `requesting_origin` for
   // `AUDIO_CAPTURE` and `VIDEO_CAPTURE`.
   // `render_frame_host->GetMainFrame()->GetLastCommittedOrigin()` will be used
   // instead.
-  rfh->GetBrowserContext()
-      ->GetPermissionController()
-      ->RequestPermissionsFromCurrentDocument(
-          permission_types, rfh, request.user_gesture,
-          base::BindOnce(
-              &MediaStreamDevicesController::PromptAnsweredGroupedRequest,
-              std::move(controller)));
+  if (previously_approved) {
+    controller->PromptAnsweredGroupedRequest({blink::mojom::PermissionStatus::GRANTED /*audio*/,
+                                              blink::mojom::PermissionStatus::GRANTED /*video*/});
+  } else {
+    rfh->GetBrowserContext()
+    ->GetPermissionController()
+    ->RequestPermissionsFromCurrentDocument(
+        permission_types, rfh, request.user_gesture,
+        base::BindOnce(
+            &MediaStreamDevicesController::PromptAnsweredGroupedRequest,
+            std::move(controller)));
+  }
 }
 
 MediaStreamDevicesController::~MediaStreamDevicesController() {
@@ -435,6 +443,7 @@ bool MediaStreamDevicesController::PermissionIsBlockedForReason(
     return false;
   }
 
+#if 0
   // TODO(raymes): This function wouldn't be needed if
   // PermissionManager::RequestPermissions returned a denial reason.
   content::PermissionResult result =
@@ -445,6 +454,7 @@ bool MediaStreamDevicesController::PermissionIsBlockedForReason(
     DCHECK_EQ(blink::mojom::PermissionStatus::DENIED, result.status);
     return true;
   }
+#endif
   return false;
 }
 
diff --git a/components/webrtc/media_stream_devices_controller.h b/components/webrtc/media_stream_devices_controller.h
index b4258f59081c5d99b9c3edf02ca538499a5a435e..3bb6ac4e27fb39283d71a46dd3af7b9f7258d1e2 100644
--- a/components/webrtc/media_stream_devices_controller.h
+++ b/components/webrtc/media_stream_devices_controller.h
@@ -48,7 +48,8 @@ class MediaStreamDevicesController {
   // synchronously or asynchronously returned via |callback|.
   static void RequestPermissions(const content::MediaStreamRequest& request,
                                  MediaStreamDeviceEnumerator* enumerator,
-                                 ResultCallback callback);
+                                 ResultCallback callback,
+                                 bool previously_approved = false);
 
   ~MediaStreamDevicesController();