Pull in Chromium's version of GatherPixelRefs

https://codereview.chromium.org/134473002/



git-svn-id: http://skia.googlecode.com/svn/trunk@13038 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/utils.gyp b/gyp/utils.gyp
index 608262e..ebac571 100644
--- a/gyp/utils.gyp
+++ b/gyp/utils.gyp
@@ -42,6 +42,7 @@
         '../include/utils/SkDebugUtils.h',
         '../include/utils/SkDeferredCanvas.h',
         '../include/utils/SkDumpCanvas.h',
+        '../include/utils/SkGatherPixelRefsAndRects.h',
         '../include/utils/SkInterpolator.h',
         '../include/utils/SkLayer.h',
         '../include/utils/SkMatrix44.h',
@@ -76,6 +77,7 @@
         '../src/utils/SkDeferredCanvas.cpp',
         '../src/utils/SkDumpCanvas.cpp',
         '../src/utils/SkFloatUtils.h',
+        '../src/utils/SkGatherPixelRefsAndRects.cpp',
         '../src/utils/SkInterpolator.cpp',
         '../src/utils/SkLayer.cpp',
         '../src/utils/SkMatrix44.cpp',