Experimental flag for HiDPI-aware PDF Viewer

Experimental flag for HiDPI-aware PDF Viewer

Adds a flag --enable-hidpi-pdf-plugin so HiDPI rendering in the PDF Viewer can
be controlled by this flag.

Add a pepper priv interface to query the flag.

BUG=114674
TEST=Manual

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=148567

[Josh Horwich, 2012-07-18 01:49:58]

Please take a look.

Also, note I did not go through the effort of version-bumping ppb_pdf.h, as that
appears to be the practice historically for PPB_PDF (see r117699 or r81822 for
example). Of course this means a version of PDF viewer that uses the new API and
runs with an older chrome will likely crash - let me know if I should go through
the effort of new/old versions of the PPB_PDF struct + adding code to the plugin
to gracefully handle either.

[Josh Horwich, 2012-07-20 02:27:49]

Gentle ping - I'd like to move this one forward so I can land experimental
support in PDF viewer. Please let me know if someone else should review.

[Josh Horwich, 2012-07-24 17:59:22]

Ping - Brett, are you the right one to review this or should I find another?
Thank you!

[brettw, 2012-07-25 17:50:37]

Sorry for the delay, LGTM

http://codereview.chromium.org/10802004/diff/1/ppapi/c/private/ppb_pdf.h
File ppapi/c/private/ppb_pdf.h (right):

http://codereview.chromium.org/10802004/diff/1/ppapi/c/private/ppb_pdf.h#newc...
ppapi/c/private/ppb_pdf.h:14: #define PPB_PDF_INTERFACE "PPB_PDF;1"
Can you rev the version number since you changed this interface?

[commit-bot: I haz the power, 2012-07-25 21:56:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jhorwich@chromium.org/10802004/1

[commit-bot: I haz the power, 2012-07-25 21:56:42]

Presubmit check for 10802004-1 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit Warnings **
Missing PPAPI IDL for private interface, please generate IDL:

***************
  ppapi/c/private/ppb_pdf.h
***************

Presubmit checks took 2.3s to calculate.

[Josh Horwich, 2012-07-25 22:00:43]

Note for posterity on why version number isn't rev'd here.

https://chromiumcodereview.appspot.com/10802004/diff/1/ppapi/c/private/ppb_pdf.h
File ppapi/c/private/ppb_pdf.h (right):

https://chromiumcodereview.appspot.com/10802004/diff/1/ppapi/c/private/ppb_pd...
ppapi/c/private/ppb_pdf.h:14: #define PPB_PDF_INTERFACE "PPB_PDF;1"
On 2012/07/25 17:50:37, brettw wrote:
> Can you rev the version number since you changed this interface?

Based on offline conversation, I'll leave the version number the same as we are
appending a method and leaving the rest of the struct alone - this isn't ideal
since consumers of this API (PDF viewer) won't be able to disambiguate
older/newer, however this lets us avoid adding multiple versions for things like
pepper_flash_component_installer.cc  .

[Josh Horwich, 2012-07-25 22:33:06]

On 2012/07/25 22:00:43, Josh Horwich wrote:
> Note for posterity on why version number isn't rev'd here.
> 
>
https://chromiumcodereview.appspot.com/10802004/diff/1/ppapi/c/private/ppb_pdf.h
> File ppapi/c/private/ppb_pdf.h (right):
> 
>
https://chromiumcodereview.appspot.com/10802004/diff/1/ppapi/c/private/ppb_pd...
> ppapi/c/private/ppb_pdf.h:14: #define PPB_PDF_INTERFACE "PPB_PDF;1"
> On 2012/07/25 17:50:37, brettw wrote:
> > Can you rev the version number since you changed this interface?
> 
> Based on offline conversation, I'll leave the version number the same as we
are
> appending a method and leaving the rest of the struct alone - this isn't ideal
> since consumers of this API (PDF viewer) won't be able to disambiguate
> older/newer, however this lets us avoid adding multiple versions for things
like
> pepper_flash_component_installer.cc  .

Also, there was a similar discussion apparently last time we added a function to
the interface - see comments #19 and up in
http://codereview.chromium.org/9139024