Remove Windows-related GN build configuration

build/toolchain/goma.gni

Index: build/toolchain/goma.gni
diff --git a/build/toolchain/goma.gni b/build/toolchain/goma.gni
index c0f4cf2825289f9bccaba909318d1e1d535b9f55..fd61ba73e7d00723b37a12a53acc6d21309b82aa 100644
--- a/build/toolchain/goma.gni
+++ b/build/toolchain/goma.gni
@@ -11,12 +11,6 @@ declare_args() {
   # Set to true to enable distributed compilation using Goma.
   use_goma = false
 
-  # Set the default value based on the platform.
-  if (is_win) {
-    # Absolute directory containing the Goma source code.
-    goma_dir = "C:\goma\goma-win"
-  } else {
-    # Absolute directory containing the Goma source code.
-    goma_dir = getenv("HOME") + "/goma"
-  }
+  # Absolute directory containing the Goma source code.
+  goma_dir = getenv("HOME") + "/goma"
 }