Revert of Move remote platforms creation logic from android_browser_finder to platform

Revert of Move remote platforms creation logic from android_browser_finder to platform (patchset #9 id:260001 of https://codereview.chromium.org/522553002/)

Reason for revert:
Speculative revert due to regression.

BUG=419901
Original issue's description:
> Move remote platforms creation logic from android_browser_finder to platform
> 
> Previously, creation of platforms is done in browser_finder
> classes. This patch aims to detach the coupling between
> creating browsers from platform by moving such methods to  platform.
> Also modify android_platform_backend so it owns the adb instance.
> 
> SHERRIFS: reverting this patch will require reverting https://codereview.chromium.org/541693004/ first.
> 
> BUG=413637
> 
> Committed: https://crrev.com/5289ba2d6a2c1eb3f429673ac0088f658d8aee5a
> Cr-Commit-Position: refs/heads/master@{#296310}

TBR=tonyg@chromium.org,nduca@chromium.org,dtu@chromium.org,achuith@chromium.org,chrishenry@google.com


BUG=413637

[nednguyen, 2014-10-08 18:05:15]

Created Revert of Move remote platforms creation logic from
android_browser_finder to platform