Make Gr[Op]MemoryPool allocate itself into its initial block.

Saves one heap allocation per DDL recorded.

Change-Id: I9393aedc3b48031cd2ea5f0160b107915077099a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/259419
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
diff --git a/src/gpu/GrProcessor.cpp b/src/gpu/GrProcessor.cpp
index aae1029..4b7b2b1 100644
--- a/src/gpu/GrProcessor.cpp
+++ b/src/gpu/GrProcessor.cpp
@@ -116,7 +116,7 @@
 #endif
 
     GrMemoryPool* pool() const {
-        static GrMemoryPool* gPool = new GrMemoryPool(4096, 4096);
+        static GrMemoryPool* gPool = GrMemoryPool::Make(4096, 4096).release();
         return gPool;
     }
 };