aura: Make aura_unittests opt into real GL NullDraw contexts.

This breaks the dependency on the TestCompositor for
this test suite. Once it's no longer in use by any test
suite, we can remove it.

R=sky@chromium.org,ben@chromium.org
BUG=270918

Review URL: https://codereview.chromium.org/172623003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252945 0039d316-1c4b-4281-b951-d872f2087c98
Fileapi: Add alternate code path to cleanly support streaming backends.

This adds the fileapi infrastructure changes kinuko recommended in the comments to: https://codereview.chromium.org/107833003/

TBR=sky
BUG=110119

Review URL: https://codereview.chromium.org/165943010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252946 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252946
Files.app: Remove the flag of file-manager-show-checkboxes.

The JavaScript code related with the flag has already removed.

BUG=344743
TEST=none

Review URL: https://codereview.chromium.org/177363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252947 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252947