Add blimp to root GN check_targets

blimp/engine/common/blimp_user_agent.cc

Index: blimp/engine/common/blimp_user_agent.cc
diff --git a/blimp/engine/common/blimp_user_agent.cc b/blimp/engine/common/blimp_user_agent.cc
new file mode 100644
index 0000000000000000000000000000000000000000..85182e0abf794a4ce4a52308881e9abd75d282c2
--- /dev/null
+++ b/blimp/engine/common/blimp_user_agent.cc
@@ -0,0 +1,32 @@
+// 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.
+
+#include "blimp/engine/common/blimp_user_agent.h"
+
+#include <string>
+
+#include "components/version_info/version_info.h"
+#include "content/public/common/user_agent.h"
+
+namespace blimp {
+namespace engine {
+
+namespace {
+
+std::string client_os_info = "Linux; Android 5.1.1";

[Wez, 2016/04/26 23:34:02]

Won't this cause an initializer?

Why do we even need a global OS info - surely this is something that
BrowserMainParts or similar should hold?

[nyquist, 2016/04/27 00:56:39]

It's part of EngineSettingsMessage, so we could move it somewhere else (the call
to SetClientOSInfo below is where we're handling the proto that contains this
data). I'll file a bug to do this as a follow-up, since this CL is just moving
stuff around.

+
+}  // namespace
+
+std::string GetBlimpEngineUserAgent() {
+  return content::BuildUserAgentFromOSAndProduct(
+      client_os_info,
+      version_info::GetProductNameAndVersionForUserAgent() + " Mobile");
+}
+
+void SetClientOSInfo(std::string os_version_info) {
+  client_os_info = os_version_info;
+}
+
+}  // namespace engine
+}  // namespace blimp