Don't depend on /net for error codes in sky viewer.

sky/viewer/platform/net_constants.h

Index: sky/viewer/platform/net_constants.h
diff --git a/sky/viewer/platform/net_constants.h b/sky/viewer/platform/net_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..15a22704450d9ce1f4e30a0787c88c4a492df076
--- /dev/null
+++ b/sky/viewer/platform/net_constants.h
@@ -0,0 +1,16 @@
+// Copyright 2015 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.
+
+#ifndef SKY_VIEWER_PLATFORM_NET_CONSTANTS_H_
+#define SKY_VIEWER_PLATFORM_NET_CONSTANTS_H_
+
+namespace sky {
+// This corresponds to ERR_ABORTED in net/base/net_error_list.h.
+// TODO(ppi): declare an enum in the network service mojom so that the clients
+// don't need to hard-code these values.
+const int32_t kNetErrorAborted = -3;
+
+const char kNetErrorDomain[] = "net";
+}  // namespace sky
+#endif  // SKY_VIEWER_PLATFORM_NET_CONSTANTS_H_