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/FrameManager.js

@@ -21,7 +21,7 @@ const helper = require('./helper');
 
 class FrameManager extends EventEmitter {
   /**
-   * @param {!Connection} client
+   * @param {!Session} client
    * @param {!Object} frameTree
    * @param {!Mouse} mouse
    */
@@ -144,7 +144,7 @@ FrameManager.Events = {
  */
 class Frame {
   /**
-   * @param {!Connection} client
+   * @param {!Session} client
    * @param {!Mouse} mouse
    * @param {?Frame} parentFrame
    * @param {string} frameId