Build nacl_helper_nonsfi with GN

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index e60c015cfae028f4b4f2882ded0a64d2e5e0a519..9d245c2690b36c8f61d28021e29dcdfb82f63e67 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -450,6 +450,30 @@ config("compiler_cpu_abi") {
         ]
         ldflags += [ "-mips64r2" ]
       }
+    } else if (current_cpu == "pnacl" && is_nacl_nonsfi) {
+      if (target_cpu == "x86" || target_cpu == "x64") {
+        cflags += [
+          "-arch",
+          "x86-32-nonsfi",
+          "--pnacl-bias=x86-32-nonsfi",
+          "--target=i686-unknown-nacl",
+        ]
+        ldflags += [
+          "-arch",
+          "x86-32-nonsfi",
+          "--target=i686-unknown-nacl",
+        ]
+      } else if (target_cpu == "arm") {
+        cflags += [
+          "-arch",
+          "arm-nonsfi",
+          "--pnacl-bias=arm-nonsfi",
+        ]
+        ldflags += [
+          "-arch",
+          "arm-nonsfi",
+        ]
+      }
     }
   }
 
@@ -753,6 +777,14 @@ config("default_warnings") {
         "-Wno-bitfield-width",
       ]
     }
+
+    if (is_nacl_nonsfi) {
+      cflags += [
+        # TODO(phosek): Enable after https://codereview.chromium.org/1419373002/
+        # is rolled into Chrome.
+        "-Wno-sign-compare",
+      ]
+    }
   }
 }