Revert "Remove GrContext"

This reverts commit 2edf18d818708509809f4be17a2f5abd6d93af2b.

Reason for revert: breaking wasm-debugger

Original change's description:
> Remove GrContext
>
> Woo!
>
> Change-Id: Ifa3ff7e79c7048c2f1d808cc9705593d72886f08
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/326436
> Auto-Submit: Adlai Holler <adlai@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,robertphillips@google.com,adlai@google.com

Change-Id: Ie05bda5dad7fb5d369ebe579d2e009fdb99c0729
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/326941
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/samplecode/Sample.cpp b/samplecode/Sample.cpp
index a69de8e..2a6e6a1 100644
--- a/samplecode/Sample.cpp
+++ b/samplecode/Sample.cpp
@@ -12,7 +12,7 @@
 #if SK_SUPPORT_GPU
 #   include "include/gpu/GrDirectContext.h"
 #else
-class GrDirectContext;
+class GrContext;
 #endif
 
 //////////////////////////////////////////////////////////////////////////////
@@ -49,7 +49,7 @@
         SkAutoCanvasRestore acr(canvas, true);
         this->onDrawContent(canvas);
 #if SK_SUPPORT_GPU
-        // Ensure the context doesn't combine GrDrawOps across draw loops.
+        // Ensure the GrContext doesn't combine GrDrawOps across draw loops.
         if (auto direct = GrAsDirectContext(canvas->recordingContext())) {
             direct->flushAndSubmit();
         }