Add ability to ninepatch blurred rounded rectangle

Speed up drawing large blurry round rectangles by converting them to
nine patches.

SkDraw:
Add drawRRect.

SkBitmapDevice:
Call SkDraw::drawRRect instead of converting SkRRect to an SkPath.

SkMaskFilter/SkBlurMaskFilter:
Create a nine patch of a blurred round rect and draw it instead of
drawing the entire thing.

SkPDFDevice:
Override drawRRect to perform the old behavior in
SkBitmapDevice::drawRect.

Depends on https://codereview.chromium.org/52703003

Tests are in https://codereview.chromium.org/52793005

BUG=https://b.corp.google.com/issue?id=11174385
R=reed@google.com, robertphillips@google.com

Review URL: https://codereview.chromium.org/48623006

git-svn-id: http://skia.googlecode.com/svn/trunk@12198 2bbb7eff-a529-9590-31e7-b0007b416f81
8 files changed