Stop linking in desktop/main.cc into the Android build.

shell/android/main.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "shell/android/main.h"
 
 #include "base/android/fifo_utils.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
@@ skipping 196 matching lines @@
   base::CommandLine::ForCurrentProcess()->AppendArg(
       base::android::ConvertJavaStringToUTF8(env, jurl));
 }
 
 bool RegisterShellMain(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace shell
 }  // namespace mojo
+
+// TODO(vtl): Even though main() should never be called, mojo_shell fails to
+// link without it. Figure out if we can avoid this.
+int main(int argc, char** argv) {
+  NOTREACHED();
+}