DM: add --multiPage option

DM: add --multiPage option

Motivation: I want to switch back to single-page output by default for
direct comparison to raster backends in Gold.

I can still test the multi-page option via a command-line switch.

BUG=skia:3721
Committed: https://skia.googlesource.com/skia/+/7e79818137f2173302d6476a6127525b11684ec2

[hal.canary, 2015-04-14 20:42:13]

halcanary@google.com changed reviewers:
+ mtklein@google.com

[hal.canary, 2015-04-14 20:42:14]

PTAL

[hal.canary, 2015-04-14 20:46:24]

The CQ bit was checked by halcanary@google.com to run a CQ dry run

[mtklein, 2015-04-14 20:46:27]

https://codereview.chromium.org/1063873004/diff/1/dm/DMSrcSink.cpp
File dm/DMSrcSink.cpp (right):

https://codereview.chromium.org/1063873004/diff/1/dm/DMSrcSink.cpp#newcode373
dm/DMSrcSink.cpp:373: 
Let's just DEFINE_bool(multiPage, false, "...") here?  Seems like less plumbing.
 No need to involve DM.cpp unless you're going to run in both modes in the same
run of DM.

[commit-bot: I haz the power, 2015-04-14 20:46:55]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063873004/1

[hal.canary, 2015-04-14 20:50:03]

https://codereview.chromium.org/1063873004/diff/1/dm/DMSrcSink.cpp
File dm/DMSrcSink.cpp (right):

https://codereview.chromium.org/1063873004/diff/1/dm/DMSrcSink.cpp#newcode373
dm/DMSrcSink.cpp:373: 
On 2015/04/14 20:46:27, mtklein wrote:
> Let's just DEFINE_bool(multiPage, false, "...") here?  Seems like less
plumbing.
>  No need to involve DM.cpp unless you're going to run in both modes in the
same
> run of DM.

Done.

[mtklein, 2015-04-14 20:55:11]

lgtm

[hal.canary, 2015-04-14 20:55:46]

The CQ bit was checked by halcanary@google.com

[commit-bot: I haz the power, 2015-04-14 20:56:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063873004/20001

[commit-bot: I haz the power, 2015-04-14 21:06:23]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/7e79818137f2173302d6476a6127525b11684ec2