Add ClientConfig proto, and JSON generation/parsing.

components/data_reduction_proxy/proto/client_config.proto

+// 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.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package data_reduction_proxy;
+
+// The client configuration information for using the Data Saver service.
+message ClientConfig {
+  // An opaque per-session key assigned by the server which permits use of the
+  // Data Saver HTTP proxy servers.
+  optional string session_key = 1;
+  // The time at which the secure_session_key is no longer valid. This is
+  // enforced by the Data Saver service, and is provided to permit the client
+  // to request a new session key prior to expiration.
+  optional Timestamp expire_time = 2;
+  // The DataSaver proxy configuration that is valid for the session.
+  optional ProxyConfig proxy_config = 3;

[bengr, 2015/03/19 16:31:15]

Where do you say what kind of traffic should be proxied? I.e., how would we
extend this to having a configuration for HTTPS traffic?

[jeremyim, 2015/03/20 16:21:12]

Line 42: // Provides proxy server information for HTTP URIs.

+}
+
+// A Timestamp represents a point in time independent of any time zone
+// or calendar, represented as seconds and fractions of seconds at
+// nanosecond resolution in UTC Epoch time.

[sclittle, 2015/03/18 20:31:51]

Why do you need nanosecond resolution? Are microseconds really too coarse for
determining when to request a new session key?

[jeremyim, 2015/03/20 16:21:12]

We don't need it; however, the service definition defines its presence.

+message Timestamp {
+  // Represents seconds of UTC time since Unix epoch
+  // 1970-01-01T00:00:00Z. Must be from from 0001-01-01T00:00:00Z to
+  // 9999-12-31T23:59:59Z inclusive.
+  optional int64 seconds = 1;
+
+  // Non-negative fractions of a second at nanosecond resolution. Negative
+  // second values with fractions must still have non-negative nanos values
+  // that count forward in time. Must be from 0 to 999,999,999
+  // inclusive.
+  optional int32 nanos = 2;

[bengr, 2015/03/19 16:31:15]

Why not use uint32?

[jeremyim, 2015/03/20 16:21:12]

Another restriction due to the service definition.

+}
+
+// Data Saver proxy configuration.
+message ProxyConfig {
+  // Provides proxy server information for HTTP URIs.
+  repeated ProxyServer http_proxy_servers = 1;
+}
+
+// Configuration information for a specific proxy server.
+message ProxyServer {
+  // The scheme of the proxy server.
+  enum ProxyScheme {
+    // The proxy scheme is unspecified.
+    UNSPECIFIED = 0;
+    // HTTP
+    HTTP = 1;
+    // HTTPS
+    HTTPS = 2;
+    // HTTPS over QUIC
+    QUIC = 3;
+  }
+
+  // The scheme for the proxy server.
+  optional ProxyScheme scheme = 1;
+  // The host name for the proxy server.
+  optional string host = 2;
+  // The port number for the proxy server.
+  optional int32 port = 3;
+}
+
+// Request object to create a client configuration object.
+message CreateClientConfigRequest {
+}