Revert "Add initial version of GrResourceAllocator's free pool"

This reverts commit 6ec9a4ffe43910551d15ddc95150472aabbc8b74.

Reason for revert: Maybe breaking iOS bots

Original change's description:
> Add initial version of GrResourceAllocator's free pool
> 
> Change-Id: Ibd60303ffb1d3ea814dad0cee3a521f94da63ca8
> Reviewed-on: https://skia-review.googlesource.com/24262
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>

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

Change-Id: I0195f64503a6f2f7b416f75b57fb9141e5b9f796
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/25540
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/include/private/GrSurfaceProxy.h b/include/private/GrSurfaceProxy.h
index 71eaf13..f899f75 100644
--- a/include/private/GrSurfaceProxy.h
+++ b/include/private/GrSurfaceProxy.h
@@ -329,6 +329,7 @@
 
     bool isWrapped_ForTesting() const;
 
+    SkDEBUGCODE(bool isInstantiated() const { return SkToBool(fTarget); })
     SkDEBUGCODE(void validate(GrContext*) const;)
 
     // Provides access to functions that aren't part of the public API.
@@ -367,8 +368,6 @@
         return this->internalHasPendingWrite();
     }
 
-    void computeScratchKey(GrScratchKey*) const;
-
     virtual sk_sp<GrSurface> createSurface(GrResourceProvider*) const = 0;
     void assign(sk_sp<GrSurface> surface);