Revert "Android: Delete in-product help for media download code"

This reverts commit b011f9b2c886d20f519cc2208e3d577a40098d7c.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 632842 as the
culprit for failures in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyRAsSDVdmU3VzcGVjdGVkQ0wiMWNocm9taXVtL2IwMTFmOWIyYzg4NmQyMGY1MTljYzIyMDhlM2Q1NzdhNDAwOThkN2MM

Sample Failed Build: https://ci.chromium.org/buildbot/chromium/win32-rel/11315

Sample Failed Step: compile

Original change's description:
> Android: Delete in-product help for media download code
> 
> In-product help system was determined not to be launched.
> This CL reverts https://crrev.com/2943983003 which added
> the functionality for media download.
> 
> Bug: 715185, 889682
> Change-Id: I7478eb2438023febd894560b18b6c380f81577e2
> Reviewed-on: https://chromium-review.googlesource.com/c/1367065
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Reviewed-by: Stephen Chenney <schenney@chromium.org>
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
> Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
> Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#632842}

Change-Id: I6af075a801126a11c863f9955105cca0a60e1968
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 715185, 889682
Reviewed-on: https://chromium-review.googlesource.com/c/1476126
Cr-Commit-Position: refs/heads/master@{#632848}
37 files changed