Fix SkTextBlob offset semantics.

Fix SkTextBlob offset semantics.

Implement proper x/y drawTextBlob() handling by plumbing a
drawPosText() offset parameter (to act as an additional glyph pos
translation) throughout the device layer.

The new offset superceeds the existing constY, with a minor semantic
tweak: whereas previous implementations were ignoring constY in 2D
positioning mode (scalarsPerGlyph == 2), now the offset is always
observed, in all positioning modes. We can do this because existing
drawPosText() clients always pass constY == 0 for full positioning mode.

R=reed@google.com, jvanverth@google.com, robertphillips@google.com

Committed: https://skia.googlesource.com/skia/+/c13bc571d3e61a43b87eb97f0719abd304cafaf2

[f(malita), 2014-09-24 21:51:22]

This changes the SkDevice API and requires a Chromium update to be included with
the roll: https://codereview.chromium.org/599913003.

[f(malita), 2014-09-25 18:16:22]

fmalita@chromium.org changed reviewers:
+ bsalomon@google.com

[reed1, 2014-09-25 19:04:40]

Note : since we have "branched", you won't be able to update Chrome/Blink for
this until after Chrome has also branched (at which time we will turn back on
our AutoRoller)

lgtm

[f(malita), 2014-09-26 14:33:41]

Committed patchset #2 (id:20001) manually as c13bc57 (presubmit successful).

[robertphillips, 2014-09-29 11:48:09]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/609223003/ by robertphillips@google.com.

The reason for reverting is: Breaking the Chrome builds with the error:

[14:54:14.317833] ../../skia/ext/pixel_ref_utils.cc:221:16: error: 'drawPosText'
marked 'override' but does not override any member functions
[14:54:14.318022]   virtual void drawPosText(const SkDraw& draw,
[14:54:14.318082]                ^.

[reed1, 2014-09-29 14:05:23]

On 2014/09/29 11:48:09, robertphillips wrote:
> A revert of this CL (patchset #2 id:20001) has been created in
> https://codereview.chromium.org/609223003/ by
mailto:robertphillips@google.com.
> 
> The reason for reverting is: Breaking the Chrome builds with the error:
> 
> [14:54:14.317833] ../../skia/ext/pixel_ref_utils.cc:221:16: error:
'drawPosText'
> marked 'override' but does not override any member functions
> [14:54:14.318022]   virtual void drawPosText(const SkDraw& draw,
> [14:54:14.318082]                ^.

can we somehow remove the need for this device subclass? (for this and future
refactorings)

[f(malita), 2014-09-29 14:36:14]

On 2014/09/29 14:05:23, reed1 wrote:
> On 2014/09/29 11:48:09, robertphillips wrote:
> > A revert of this CL (patchset #2 id:20001) has been created in
> > https://codereview.chromium.org/609223003/ by
> mailto:robertphillips@google.com.
> > 
> > The reason for reverting is: Breaking the Chrome builds with the error:
> > 
> > [14:54:14.317833] ../../skia/ext/pixel_ref_utils.cc:221:16: error:
> 'drawPosText'
> > marked 'override' but does not override any member functions
> > [14:54:14.318022]   virtual void drawPosText(const SkDraw& draw,
> > [14:54:14.318082]                ^.
> 
> can we somehow remove the need for this device subclass? (for this and future
> refactorings)

Possibly: I'm not all that familiar with GatherPixelRefDevice, but at a glance
it seems to be replaceable with a canvas subclass.