Retract GrSurfaceDrawContext.h a bit

This CL just pulls GrSurfaceDrawContext.h out of headers and .cpp files where possible.

TBR=brianosman@google.com
Bug: skia:11837
Change-Id: Ib96f3619e3a50091516f81ae48f956fe83c05aff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/431384
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/GrSoftwarePathRenderer.cpp b/src/gpu/GrSoftwarePathRenderer.cpp
index 885f377..bd96e59 100644
--- a/src/gpu/GrSoftwarePathRenderer.cpp
+++ b/src/gpu/GrSoftwarePathRenderer.cpp
@@ -21,6 +21,7 @@
 #include "src/gpu/GrProxyProvider.h"
 #include "src/gpu/GrRecordingContextPriv.h"
 #include "src/gpu/GrSWMaskHelper.h"
+#include "src/gpu/GrSurfaceDrawContext.h"
 #include "src/gpu/GrUtil.h"
 #include "src/gpu/SkGr.h"
 #include "src/gpu/effects/GrTextureEffect.h"