Allow passing mock FrameLoaderClient to DummyPageHolder.

Allow passing mock FrameLoaderClient to DummyPageHolder.

This CL has three parts:
- DummyPageHolder can be created with a given FrameLoaderClient instance.
- EmptyFrameLoaderClient is no longer FINAL so it can be used for mocks.
- fix dependency breakage following the move of EmptyClients.h in the cpp.

BUG=None

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181312

[mlamouri (slow - plz ping), 2014-08-27 17:15:45]

Review ping. Let me know if you want me to not move "EmptyClients.h" out of the
header. This is the cause of the diff being way bigger than it should.

[mlamouri (slow - plz ping), 2014-09-02 08:51:56]

mlamouri@chromium.org changed reviewers:
+ dcheng@chromium.org

[mlamouri (slow - plz ping), 2014-09-02 08:51:57]

dcheng@, do you think this would be interesting to have even though I will not
have a direct use of it for the moment?

[mlamouri (slow - plz ping), 2014-09-02 21:33:36]

On 2014/09/02 19:33:04, abarth wrote:

Adam, you left a blank comment, I assume that wasn't on purpose?

[abarth-chromium, 2014-09-02 21:45:17]

Sorry, I meant to LGTM

[mlamouri (slow - plz ping), 2014-09-03 10:45:58]

The CQ bit was checked by mlamouri@chromium.org

[commit-bot: I haz the power, 2014-09-03 10:46:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mlamouri@chromium.org/467943005/20001

[commit-bot: I haz the power, 2014-09-03 11:55:23]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/25361)

[commit-bot: I haz the power, 2014-09-03 13:06:03]

Committed patchset #2 (id:20001) as 181312