Revert 239921 "Revert 239759 "The comment in base64.h implies th..."

Revert 239921 "Revert 239759 "The comment in base64.h implies th..."

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Reverting the revert. Congrats, the original CL wasn't the cause for the failure; sorry for the mess.
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> Revert 239759 "The comment in base64.h implies that base::Base64..."
> 
> > The comment in base64.h implies that base::Base64Encode() can return false, but
> > this cannot happen in practice. Fix the comment.
> > 
> > The implementation of Base64Encode() attempts to check for the return value
> > MODP_B64_ERROR as a failure, but modp_b64_encode() cannot return this
> > value. Remove the check.
> > 
> > Remove unneeded integer cast.
> > 
> > Change the return type to void.
> > 
> > BUG=323357
> > TEST=base_unittests, compile all
> > TBR=jochen@chromium.org,miket@chromium.org,joi@chromium.org,akalin@chromium.org,sergeyu@chromium.org
> > 
> > Review URL: https://codereview.chromium.org/86913002
> 
> TBR=ricea@chromium.org
> 
> Review URL: https://codereview.chromium.org/101113004

TBR=vadimt@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=239944

[vadimt, 2013-12-11 01:48:55]

Committed patchset #1 manually as r239944.

[vadimt, 2013-12-11 01:56:38]

+ original author