GN: Remove android arguments from the conditional

build/config/android/config.gni

Index: build/config/android/config.gni
diff --git a/build/config/android/config.gni b/build/config/android/config.gni
index 9fc6c27d0de4676d0517c1a0cdabb6295d312352..c7408127276ec6fa8723c82f74d4fc6a5aeda701 100644
--- a/build/config/android/config.gni
+++ b/build/config/android/config.gni
@@ -3,16 +3,21 @@
 # found in the LICENSE file.
 
 # This file contains common system config stuff for the Android build.
-if (is_android) {
-  declare_args() {
-    android_src = ""
 
-    # This is set when building the Android WebView inside the Android build
-    # system, using the 'android' gyp backend. The WebView code is still built
-    # when this is unset, but builds using the normal chromium build system.
-    is_android_webview_build = false
-  }
+# TODO(brettw) bug 341772 put this into the is_android block when the toolchain
+# stuff is fixed in the GYP generator. The problem is that when we redo the
+# build in host mode, the OS is not android and the declarations are never
+# seen, which throws an error because these arguments are specified.
+declare_args() {
+  android_src = ""
 
+  # This is set when building the Android WebView inside the Android build
+  # system, using the 'android' gyp backend. The WebView code is still built
+  # when this is unset, but builds using the normal chromium build system.
+  is_android_webview_build = false
+}
+
+if (is_android) {
   if (is_android_webview_build) {
     assert(android_src != "",
            "You must specify android_src for an Android WebView build.")