Remove //net (except for Android test stuff) and sdch

Remove //net (except for Android test stuff) and sdch

These aren't used in this repository any more. The bits of test
infrastructure under //net/android and //net/test can go away after we
update our snapshot of //build not to reference these any more.

R=ppi@chromium.org
BUG=456130
Committed: https://chromium.googlesource.com/external/mojo/+/795b372f0a6c8af5cbae306b80c2d347897c4dcf

[ppi, 2015-03-09 20:31:26]

lgtm

[jamesr, 2015-03-09 20:32:22]

Committed patchset #1 (id:1) manually as
795b372f0a6c8af5cbae306b80c2d347897c4dcf (presubmit successful).