Revert 209420 "Factor out content shell and tests into a standal..."

Revert 209420 "Factor out content shell and tests into a standal..."

> Factor out content shell and tests into a standalone gyp
> 
> This simplifies using components in Content Shell.  As components can
> depend on the content layer, trying to use a component from Content Shell
> results in a cross-reference of gyp files which isn't allowed on Mac.
> 
> TBR=joi,robertshield (trivial one-line renames in gyp files)
> 
> Review URL: https://chromiumcodereview.appspot.com/17366006

TBR=mnaganov@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=209770