Add dep crx to GN target create_dist_mac (#31702)

Add dep crx to target create_dist_mac

This lets us use `npm run create_dist` to build the crx for macOS.

build/mac/BUILD.gn

@@ -401,16 +401,17 @@ group("create_dist_mac") {
       }
     }
   }
+  if (dmg_crx_private_key != "") {
+    deps += [ ":crx" ]
+  }
 }
 
-crx3("crx") {
-  inputs = [ dmg_path ]
-  output = "$packaged_basename.crx3"
-  base_dir = get_path_info(dmg_path, "dir")
-
-  # The private key file is not in Git for obvious reasons. It needs to be
-  # copied into this directory manually. Changing the private key requires
-  # also changing kBravePublisherKeyHash in crx_verifier.cc.
-  key = "//brave/updater/crx-private-key.der"
-  deps = [ ":package" ]
+if (dmg_crx_private_key != "") {
+  crx3("crx") {
+    inputs = [ dmg_path ]
+    output = "$packaged_basename.crx3"
+    base_dir = get_path_info(dmg_path, "dir")
+    key = dmg_crx_private_key
+    deps = [ ":package" ]
+  }
 }

build/mac/config.gni

@@ -23,6 +23,9 @@ declare_args() {
   # we have fully migrated to Omaha 4, we will remove this GN arg with a default
   # value of true.
   install_omaha4_with_pkg = false
+
+  # Path to the private key that is used to sign browser updates.
+  dmg_crx_private_key = ""
 }
 
 if (host_os == "mac") {

updater/.gitignore

@@ -1 +0,0 @@
-crx-private-key.der