Lay some groundwork for depowering SkGpuDevice's and SkImage_GpuBase's context pointer

In future Ganesh these classes will, respectively, have a RecordingContext and an ImageContext.

Change-Id: I69ced004a2edae5c410e9c00c2de6c0246699caa
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/197167
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/SkGpuDevice.h b/src/gpu/SkGpuDevice.h
index 0b1b7d9..9d60096 100644
--- a/src/gpu/SkGpuDevice.h
+++ b/src/gpu/SkGpuDevice.h
@@ -168,7 +168,7 @@
 
     GrClipStackClip clip() const { return GrClipStackClip(&this->cs()); }
 
-    const GrCaps* caps() const { return fContext->priv().caps(); }
+    const GrCaps* caps() const;
 
     /**
      * Helper functions called by drawBitmapCommon. By the time these are called the SkDraw's