Fix build issues in base/ for Android x64

This CL fixes several issues when building files under base/ for
Android x64.

BUG=346626

Review URL: https://codereview.chromium.org/179373003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254124 0039d316-1c4b-4281-b951-d872f2087c98
Add serviceworker-reviews@ to WATCHLIST

TBR=alecflett@chromium.org
NOTRY=true
BUG=none

Review URL: https://codereview.chromium.org/181823005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254125 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254124
Nukes ContextSupplement and makes PerContextData extend SupportUserData

This gives the same functionality and ownership model while making it
simpler to associate arbitrary data with a context.

BUG=none
TEST=none
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/183433002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254126 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254126