Capture page reopening (potential race condition)

[Yuu-Han]

(As we talked in Feb 5 meeting) Clicking a closed node on historymap will reopen the page and set its state to open, not adding a new node (see #148). In other words, for a newly opened page, we need to know if it is opened from a closed one in order to determine whether to create a new node.

[Yuu-Han]

In the latest implementation, the success of the capturing relies on event 1 happening earlier than event 2:

• Event 1: function chrome.tabs.create callback
  • The tab id is updated in this callback function
• Event 2: the listener observes page opening (triggered by chrome.tabs.create)
  • It tries to find a page with the same tab id (and other attributes) to decide whether to add a new node

Maybe this works because the page opening event is exposed after the create function (including the callback) is done (but not entirely sure).