Add initial framework for AssignmentSource.

This CL moves reading the command line params for engine connection
to a default AssignmentSource instead of being a part of
BlimpClientSession. This is required going forward to be able to
implement something that communicates with the real assigner.

In addition this CL also makes the connection step asynchronous
instead of happening during the construction of the
BlimpClientSession. This is important so that going forward, the
request to get an assignment does not block startup.

BUG=582668

Review URL: https://codereview.chromium.org/1648383004

Cr-Commit-Position: refs/heads/master@{#372892}

1 files changed, 76 insertions, 0 deletions

diff --git a/blimp/client/session/assignment_source.cc b/blimp/client/session/assignment_source.cc
new file mode 100644
index 0000000..271569c
--- /dev/null
+++ b/blimp/client/session/assignment_source.cc
@@ -0,0 +1,76 @@
+// 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/client/session/assignment_source.h"
+
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/location.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/strings/string_number_conversions.h"
+#include "blimp/client/app/blimp_client_switches.h"
+#include "net/base/ip_address.h"
+#include "net/base/ip_endpoint.h"
+
+namespace blimp {
+namespace {
+
+// TODO(kmarshall): Take values from configuration data.
+const char kDummyClientToken[] = "MyVoiceIsMyPassport";
+const std::string kDefaultBlimpletIPAddress = "127.0.0.1";
+const uint16_t kDefaultBlimpletTCPPort = 25467;
+
+net::IPAddress GetBlimpletIPAddress() {
+  std::string host;
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kBlimpletHost)) {
+    host = base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+        switches::kBlimpletHost);
+  } else {
+    host = kDefaultBlimpletIPAddress;
+  }
+  net::IPAddress ip_address;
+  if (!net::IPAddress::FromIPLiteral(host, &ip_address))
+    CHECK(false) << "Invalid BlimpletAssignment host " << host;
+  return ip_address;
+}
+
+uint16_t GetBlimpletTCPPort() {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kBlimpletTCPPort)) {
+    std::string port_str =
+        base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kBlimpletTCPPort);
+    uint port_64t;
+    if (!base::StringToUint(port_str, &port_64t) ||
+        !base::IsValueInRangeForNumericType<uint16_t>(port_64t)) {
+      CHECK(false) << "Invalid BlimpletAssignment port " << port_str;
+    }
+    return base::checked_cast<uint16_t>(port_64t);
+  } else {
+    return kDefaultBlimpletTCPPort;
+  }
+}
+
+}  // namespace
+
+namespace client {
+
+AssignmentSource::AssignmentSource(
+    const scoped_refptr<base::SingleThreadTaskRunner>& main_task_runner)
+    : main_task_runner_(main_task_runner) {}
+
+AssignmentSource::~AssignmentSource() {}
+
+void AssignmentSource::GetAssignment(const AssignmentCallback& callback) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  Assignment assignment;
+  assignment.ip_endpoint =
+      net::IPEndPoint(GetBlimpletIPAddress(), GetBlimpletTCPPort());
+  assignment.client_token = kDummyClientToken;
+  main_task_runner_->PostTask(FROM_HERE, base::Bind(callback, assignment));
+}
+
+}  // namespace client
+}  // namespace blimp