diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..fc4eb1b
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,13 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+
+AccessModifierOffset: -2
+ColumnLimit: 100
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 4
+PointerAlignment: Left
+TabWidth: 4
+UseTab: Never
+PenaltyExcessCharacter: 32
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
new file mode 100644
index 0000000..c8dbf77
--- /dev/null
+++ b/PREUPLOAD.cfg
@@ -0,0 +1,5 @@
+[Builtin Hooks]
+clang_format = true
+
+[Builtin Hooks Options]
+clang_format = --commit ${PREUPLOAD_COMMIT} --style file --extensions c,h,cc,cpp
diff --git a/include/system/window.h b/include/system/window.h
index 8149ca5..31a239b 100644
--- a/include/system/window.h
+++ b/include/system/window.h
@@ -317,6 +317,12 @@
      * retire info, 0 if it won't.
      */
     NATIVE_WINDOW_FRAME_TIMESTAMPS_SUPPORTS_RETIRE = 18,
+
+    /*
+     * Returns 1 if the native window is valid, 0 otherwise. native window is valid
+     * if it is safe (i.e. no crash will occur) to call any method on it.
+     */
+    NATIVE_WINDOW_IS_VALID = 19,
 };
 
 /* Valid operations for the (*perform)() hook.