Remove Chrome OS-related GN build configuration

third_party/breakpad/BUILD.gn

Index: third_party/breakpad/BUILD.gn
diff --git a/third_party/breakpad/BUILD.gn b/third_party/breakpad/BUILD.gn
index ad1011efc55c618d40dd69e3630ca229e4a24155..259e6baa44aa4ef63894e553cc9c3f48b9187fdf 100644
--- a/third_party/breakpad/BUILD.gn
+++ b/third_party/breakpad/BUILD.gn
@@ -515,12 +515,6 @@ if (is_linux || is_android) {
     configs += [ "//build/config/compiler:no_chromium_code" ]
     public_configs = [ ":client_config" ]
 
-    if (current_cpu == "arm" && is_chromeos) {
-      # Avoid running out of registers in
-      # linux_syscall_support.h:sys_clone()'s inline assembly.
-      cflags = [ "-marm" ]
-    }
-
     if (is_android) {
       sources += [ "src/common/android/breakpad_getcontext.S" ]
     }