Chrome Version       : 57.0.2987.21 (Official Build) beta (64-bit)
URLs (if applicable) : ANY
Other browsers tested: Chrome 56
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari: N/A
    Firefox: N/A
         IE: N/A
     Chrome: OK on Chrome 56 and prior

What steps will reproduce the problem?
(1) Configure Chrome to open a specific page(s) at launch, in this example I will use only two for simplicity, https://www.google.com and https://www.chromium.org
(2) Open Chrome, Chrome will open google.com and chromium.org in their own tabs
(3) Pin one or more of these tabs, in this example, pin only google.com
(4) Close and reopen Chrome
(5) Chrome will ignore the pinned tab(s) and launch the specified tabs at startup, even if the same site is already open in a pinned tab. 

What is the expected result?

Chrome should identify that the pinned tab matches the tab to be opened at launch and not open a second instance, and only open tabs that are not already open.


What happens instead?

Chrome ignores the pinned tabs and loads the sites to load at startup in new tabs, even if one or more of the sites is already open in a pinned tab.  So in the example from above with google.com and chromium.org set to launch at startup and google.com pinned from the previous session, when Chrome is opened again, google.com is opened in both its pinned tab and in a new tab.

Prior to Chrome Beta 57, if a site to load at startup is already opened in a pinned tab, it is not opened a second time upon startup.


Please provide any additional information below. Attach a screenshot if
possible.

Just configure a site to open at startup, then pin that site and close and reopen Chrome.  The site as expected will load in the pinned tab, but the exact same site will also load in a new tab.  In Chrome 56 and prior, it would only have opened the pinned tab (plus the new tab page).  Chrome Beta 57 doesn't count the startup setting as being fulfilled by a pinned tab, so it creates a new tab of the startup site in addition to the pinned tab.