Issue 304955: remove SPDY/2 code from Chrome

May have to bump this, due to  bug 318651 .

I will use this bug also to track reverting the change that re-enabled SPDY/2 from 318651.

revert in as 235898 (not sure if it'll tag this bug).

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r235898 | akalin@chromium.org | 2013-11-19T02:18:15.180687Z

Changed paths:
   M http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/chrome_switches.cc?r1=235898&r2=235897&pathrev=235898
   M http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/chrome_switches.h?r1=235898&r2=235897&pathrev=235898
   M http://src.chromium.org/viewvc/chrome/trunk/src/chrome/browser/io_thread.cc?r1=235898&r2=235897&pathrev=235898

Revert 234959 "[SPDY] Reenable SPDY/2 for M32"

> [SPDY] Reenable SPDY/2 for M32
> 
> This will be merged to the M32 branch and then reverted on trunk.
> 
> BUG= 318651 
> R=jam@chromium.org, rch@chromium.org
> 
> Review URL: https://codereview.chromium.org/71383002

TBR=akalin@chromium.org
BUG= 304955 

Review URL: https://codereview.chromium.org/75413007
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Moving all non essential bugs to the next Milestone.

Reliquishing ownership.

Reliquishing ownership.

This issue has already been moved once and is lower than Priority 1,therefore removing mstone.

Migrate from Cr-Internals-Network-SPDY to Cr-Internals-Network-HTTP2