Move SkBitmapDevice functions to their own file

https://codereview.chromium.org/23553006/



git-svn-id: http://skia.googlecode.com/svn/trunk/gyp@11022 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/core.gypi b/core.gypi
index c9deb06..6c00a56 100644
--- a/core.gypi
+++ b/core.gypi
@@ -21,6 +21,7 @@
         '<(skia_src_path)/core/SkBBoxHierarchyRecord.cpp',
         '<(skia_src_path)/core/SkBBoxHierarchyRecord.h',
         '<(skia_src_path)/core/SkBitmap.cpp',
+        '<(skia_src_path)/core/SkBitmapDevice.cpp',
         '<(skia_src_path)/core/SkBitmapFilter.h',
         '<(skia_src_path)/core/SkBitmapFilter.cpp',
         '<(skia_src_path)/core/SkBitmapHeap.cpp',