Switch FP creation over to GrRecordingContext

This CL does make use of a new GrRecordingContextPriv backdoor to break CL deadlocks. This occurs when this CL tries to create GrContext-dependent objects outside its scope.

Change-Id: I925030c818f00559d4c953ae07af53667b44aab9
Reviewed-on: https://skia-review.googlesource.com/c/192032
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrRecordingContext.cpp b/src/gpu/GrRecordingContext.cpp
index 20b857e..47adb97 100644
--- a/src/gpu/GrRecordingContext.cpp
+++ b/src/gpu/GrRecordingContext.cpp
@@ -280,3 +280,7 @@
                                                                  mipMapped, origin, surfaceProps,
                                                                  budgeted);
 }
+
+GrContext* GrRecordingContextPriv::backdoor() {
+    return (GrContext*) fContext;
+}