Convert some NetError[Tab]Helper messages to mojom

chrome/common/network_diagnostics.mojom

Index: chrome/common/network_diagnostics.mojom
diff --git a/chrome/common/network_diagnostics.mojom b/chrome/common/network_diagnostics.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..8104e08592cfbb64c9685af61d7725f7659d26b2
--- /dev/null
+++ b/chrome/common/network_diagnostics.mojom
@@ -0,0 +1,17 @@
+// Copyright 2016 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.
+
+module mojom;
+
+import "url/mojo/url.mojom";
+
+interface NetworkDiagnostics {
+  RunNetworkDiagnostics(url.mojom.Url failed_url);
+};
+
+interface NetworkDiagnosticsClient {
+  // Tells the renderer whether or not there is a local diagnostics service that
+  // can be run via calls to NetworkDiagnostics::RunNetworkDiagnostics.
+  SetCanShowNetworkDiagnosticsDialog(bool can_show);
+};