[Chromecast] Enable PROTECTED_MEDIA_IDENTIFIER permission on Cast builds

This permission is needed on Cast devices, including Linux-based builds,
but it was removed here: crrev.com/c/1045962. Restore it on Cast builds.

BUG=b/79526220
Bug: 79526220
Test: CQ

Change-Id: I0678a29e97eb003878db458dface608b6550d2fc
Reviewed-on: https://chromium-review.googlesource.com/1054334Reviewed-by: Sergey Volk <servolk@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Stephen Lanham <slan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557671}

content/browser/BUILD.gn

@@ -1783,6 +1783,10 @@ jumbo_source_set("browser") {
     ]
   }
 
+  if (is_chromeos || is_android || is_chromecast) {
+    defines += [ "ENABLE_PROTECTED_MEDIA_IDENTIFIER_PERMISSION" ]
+  }
+
   if (is_chromecast && is_linux) {
     sources += [
       "tracing/cast_tracing_agent.cc",

content/browser/permissions/permission_service_impl.cc

@@ -47,13 +47,13 @@ bool PermissionDescriptorToPermissionType(
       return true;
     }
     case PermissionName::PROTECTED_MEDIA_IDENTIFIER:
-#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
+#if defined(ENABLE_PROTECTED_MEDIA_IDENTIFIER_PERMISSION)
       *permission_type = PermissionType::PROTECTED_MEDIA_IDENTIFIER;
       return true;
 #else
       NOTIMPLEMENTED();
       return false;
-#endif
+#endif  // defined(ENABLE_PROTECTED_MEDIA_IDENTIFIER_PERMISSION)
     case PermissionName::DURABLE_STORAGE:
       *permission_type = PermissionType::DURABLE_STORAGE;
       return true;