Use IPDF_DataAvail interface to hide CPDF_DataAvail.

Use IPDF_DataAvail interface to hide CPDF_DataAvail.

Currently, no callers go through the Interface, which makes having a
separate interface class kind of pointless.  After converting callers
away from using the CPDF_DataAvail concrete class, it can be moved
from the header to the .cpp file.

R=bo_xu@foxitsoftware.com

Committed: https://pdfium.googlesource.com/pdfium/+/219e462c2a0bb9a5462c0ee43ec93ac86c9cda40

[Tom Sepez, 2015-01-22 23:00:55]

tsepez@chromium.org changed reviewers:
+ bo_xu@foxitsoftware.com

[Tom Sepez, 2015-01-22 23:00:55]

Bo, please review.  If we're going to program to interfaces, we might as well
use them otherwise it adds needless complexity.

[Bo Xu, 2015-01-22 23:35:17]

On 2015/01/22 23:00:55, Tom Sepez wrote:
> Bo, please review.  If we're going to program to interfaces, we might as well
> use them otherwise it adds needless complexity.

LGTM. Oh, I remember there are a few other instances like this, at least in XFA.

[Tom Sepez, 2015-01-23 00:24:49]

tsepez@chromium.org changed reviewers:
+ thestig@chromium.org

[Tom Sepez, 2015-01-23 00:25:03]

Lei, do you think this is worthwhile?

[Lei Zhang, 2015-01-23 00:42:44]

On 2015/01/23 00:25:03, Tom Sepez wrote:
> Lei, do you think this is worthwhile?

Sure. Consumers should be only using headers from fpdfsdk/include, but some of
them #include from ../../core/include, so CPDF* code can leak out. Right now
"CPDF_DataAvail* foo = new CPDF_DataAvail(NULL, NULL);" in
pdf/pdfium/pdfium_engine.cc compiles, but I shouldn't be able to do that.

[Tom Sepez, 2015-01-23 00:45:08]

On 2015/01/23 00:42:44, Lei Zhang wrote:
> On 2015/01/23 00:25:03, Tom Sepez wrote:
> > Lei, do you think this is worthwhile?
> 
> Sure. Consumers should be only using headers from fpdfsdk/include, but some of
> them #include from ../../core/include, so CPDF* code can leak out. Right now
> "CPDF_DataAvail* foo = new CPDF_DataAvail(NULL, NULL);" in
> pdf/pdfium/pdfium_engine.cc compiles, but I shouldn't be able to do that.

Thanks.  FYI, I checked that the patch applies and builds in standalone XFA. I
thought I also tried it under a chromium checkout -- are you saying that
pdfium_engine.cc will break?

[Tom Sepez, 2015-01-23 00:57:19]

> Thanks.  FYI, I checked that the patch applies and builds in standalone XFA. I
> thought I also tried it under a chromium checkout -- are you saying that
> pdfium_engine.cc will break?
Codesearch seems to suggest that the code fragment in #7 is a hypothetical.

[Tom Sepez, 2015-01-23 00:58:02]

Committed patchset #1 (id:1) manually as
219e462c2a0bb9a5462c0ee43ec93ac86c9cda40 (presubmit successful).

[Lei Zhang, 2015-01-23 01:04:00]

On 2015/01/23 00:57:19, Tom Sepez wrote:
> > Thanks.  FYI, I checked that the patch applies and builds in standalone XFA.
I
> > thought I also tried it under a chromium checkout -- are you saying that
> > pdfium_engine.cc will break?
> Codesearch seems to suggest that the code fragment in #7 is a hypothetical.

Indeed, sorry for being unclear. We don't reference any CPDF code in pdf/