add SkCanvas::NewRaster factory -- a very common use-case in chrome

add SkCanvas::NewRaster factory -- a very common use-case in chrome

BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=13617

[scroggo, 2014-02-27 19:16:06]

lgtm

https://codereview.chromium.org/183533004/diff/20001/include/core/SkCanvas.h
File include/core/SkCanvas.h (right):

https://codereview.chromium.org/183533004/diff/20001/include/core/SkCanvas.h#...
include/core/SkCanvas.h:55: *  else they will be initialized to 0. The caller
can access the pixels
How about initializing them to SK_ColorTRANSPARENT?

https://codereview.chromium.org/183533004/diff/20001/src/core/SkCanvas.cpp
File src/core/SkCanvas.cpp (right):

https://codereview.chromium.org/183533004/diff/20001/src/core/SkCanvas.cpp#ne...
src/core/SkCanvas.cpp:2319: bitmap.eraseColor(0);
Same.

[reed1, 2014-02-27 19:59:33]

now w/ unittest

[scroggo, 2014-02-27 20:07:43]

On 2014/02/27 19:59:33, reed1 wrote:
> now w/ unittest

LGTM

[reed1, 2014-02-27 20:14:42]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2014-02-27 20:14:46]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/reed@google.com/183533004/40001

[commit-bot: I haz the power, 2014-02-27 20:32:54]

Change committed as 13617