Port most of the remainder of //tools/android from GYP to GN

tools/android/ps_ext/BUILD.gn

Index: tools/android/ps_ext/BUILD.gn
diff --git a/components/omnibox/common/BUILD.gn b/tools/android/ps_ext/BUILD.gn
similarity index 77%
copy from components/omnibox/common/BUILD.gn
copy to tools/android/ps_ext/BUILD.gn
index 3e0af71eee45a9ae5c97e565c4f2bf2149a1ae97..6fbba19a2032311bf38978d72e7b50fb4c92d91a 100644
--- a/components/omnibox/common/BUILD.gn
+++ b/tools/android/ps_ext/BUILD.gn
@@ -2,8 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("common") {
+executable("ps_ext") {
   sources = [
-    "omnibox_focus_state.h",
+    "ps_ext.c",
   ]
 }