Move Clipboard-related code from core/dom to core/clipboard

Move Clipboard-related code from core/dom to core/clipboard

A lot of this stuff landed in dom when it was ousted from core/platform; most of
these classes would be happier in blink_platform (save for Clipboard,
DataTransferItem, and DataTransferItemList, which all have associated IDL files),
but due to a few File dependencies it's not trivial to move there.

But since it doesn't belong in dom (they're not related to Document structure),
a new clipboard directory seems the best bet.

R=abarth@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=166738

[dcheng, 2014-02-07 18:40:15]

On 2014/02/07 18:38:43, adamk wrote:

Would it make more sense to leave Clipboard where it is? It actually implements
a DOM object, unlike DataObject/Pasteboard/etc.

[adamk, 2014-02-07 18:44:53]

On 2014/02/07 18:40:15, dcheng wrote:
> Would it make more sense to leave Clipboard where it is? It actually
implements
> a DOM object, unlike DataObject/Pasteboard/etc.

The trouble is that "DOM" is overloaded. The thing you're referring to is one
meaning, which is "C++ object exposed to JavaScript in the browser". But that
applies to lots of core, such as Window (in core/frame/DOMWindow). But the "dom"
in "core/dom" generally means _document_ object model, having to do with the
Document structure itself (Nodes, Elements, etc). Since the Blink split, we've
been trying to make the directory structure in core richer (see core/events,
core/frame, core/timing). Does that make sense?

My CL description was unclear, though, and I'll rewrite it to point out that
only the non-IDL-exposed parts of this belong in blink_platform.

[abarth-chromium, 2014-02-07 18:50:19]

lgtm

[adamk, 2014-02-07 18:50:46]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2014-02-07 18:50:59]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/adamk@chromium.org/153343003/1

[adamk, 2014-02-07 21:11:50]

Committed patchset #1 manually as r166738 (presubmit successful).