Roll chromium to 492629 (#230)

This patch
- rolls chromium to 492629
- migrates connection establishing to use browser target. This migration means
  that now we have a single websocket connection to browser (implemented
  in Connection class). A connection to a particular target is
  incapsulated in a new Session class.

lib/NetworkManager.js

@@ -18,7 +18,7 @@ const helper = require('./helper');
 
 class NetworkManager extends EventEmitter {
   /**
-   * @param {!Connection} client
+   * @param {!Session} client
    */
   constructor(client) {
     super();
@@ -165,7 +165,7 @@ helper.tracePublicAPI(Request);
 
 class Response {
   /**
-   * @param {!Connection} client
+   * @param {!Session} client
    * @param {?Request} request
    * @param {!Object} payload
    */
@@ -223,7 +223,7 @@ helper.tracePublicAPI(Response);
 
 class InterceptedRequest {
   /**
-   * @param {!Connection} client
+   * @param {!Session} client
    * @param {string} interceptionId
    * @param {!Object} payload
    */