Remove GrContextPriv.h from GrRenderTargetContext.h

Change-Id: Ib3afe6d8f2f9607eededb4dd4ef9dbe305741cfb
Reviewed-on: https://skia-review.googlesource.com/c/192829
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tools/debugger/SkDebugCanvas.cpp b/tools/debugger/SkDebugCanvas.cpp
index 3a4522f..96c0de2 100644
--- a/tools/debugger/SkDebugCanvas.cpp
+++ b/tools/debugger/SkDebugCanvas.cpp
@@ -17,6 +17,7 @@
 
 #include "GrAuditTrail.h"
 #include "GrContext.h"
+#include "GrContextPriv.h"
 #include "GrRenderTargetContext.h"
 
 #define SKDEBUGCANVAS_VERSION                     1