Merge 177774

Merge 177774
> Start sending synthetic keyevents for enter and tab in Android IME
> 
> After sdk 15 Android framework no longer sends keyevents for enter and tab
> and the current spec says the dispatchKeyEvent call should only be used for
> hardware keyboard. So we stop calling ImeAdapter with dispathKeyEvent if the
> keyboard is not connected and also start sending these keyevents when a
> they are committed as a single character
> 
> BUG=166233
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/11914003

TBR=yusufo@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=178090