Marking this as a Dev blocker. Staying in the details page allows the user to start making calls to the developerPrivate API for a non existing extensions (by interacting with the details view), see screenshot of errors.

CL at https://chromium-review.googlesource.com/c/chromium/src/+/749894

Suggestions for QA testing:

## Tests that *should* navigate back to main extensions page

On the *details* page for extension X, clicking the remove row and clicking remove in the dialog should navigate back to the main extensions page.

On the *details* page for extension X and extension X is removed by right clicking on the top-chrome icon for extension X and selecting "Remove from Chrome..." the page should navigate to the main extensions page.

On the *errors* page for extension X and extension X is removed by right clicking on the top-chrome icon for extension X and selecting "Remove from Chrome..." the page should navigate to the main extensions page.


## Test that should *not* navigate back to main extensions page

If on the extensions keyboard *shortcuts* page and an extension is removed by right clicking on the top-chrome icon and selecting "Remove from Chrome..." the page should not navigate away from the shortcuts page. (The removed extension should be removed from the shortcuts page).

On the *details* page for extension X and extension Y is removed by right clicking on the top-chrome icon for extension Y and selecting "Remove from Chrome..." the page should should not navigate away from the details page for extension X.

On the *errors* page for extension X and extension Y is removed by right clicking on the top-chrome icon for extension Y and selecting "Remove from Chrome..." the page should should not navigate away from the errors page for extension X.

CL at https://chromium-review.googlesource.com/c/chromium/src/+/749894

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/287f907ff447632380426ae7421ea98913c22d16

commit 287f907ff447632380426ae7421ea98913c22d16
Author: Dave Schuyler <dschuyler@chromium.org>
Date: Fri Nov 03 04:35:25 2017

[MD extensions] navigate to main page after uninstall

This CL causes the extensions to navigate to the main (list) page when
an extension is uninstalled.

Bug:  778655 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I8c35bfb4b0f23e236b819de87adddccda154125c
Reviewed-on: https://chromium-review.googlesource.com/749894
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Dave Schuyler <dschuyler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513678}
[modify] https://crrev.com/287f907ff447632380426ae7421ea98913c22d16/chrome/browser/resources/md_extensions/manager.js
[modify] https://crrev.com/287f907ff447632380426ae7421ea98913c22d16/chrome/test/data/webui/extensions/extension_service_test.js