remove SkPurgeGlobalDiscardableMemoryPool

BUG=skia:2721
R=reed@google.com

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/495453004
diff --git a/include/core/SkImageGenerator.h b/include/core/SkImageGenerator.h
index 17477e3..4eb5cf8 100644
--- a/include/core/SkImageGenerator.h
+++ b/include/core/SkImageGenerator.h
@@ -35,12 +35,6 @@
  */
 SK_API bool SkInstallDiscardablePixelRef(SkImageGenerator*, SkBitmap* destination);
 
-/**
- *  Purges all unlocked discardable memory in Skia's global
- *  discardable memory pool.
- */
-SK_API void SkPurgeGlobalDiscardableMemoryPool();
-
 
 /**
  *  An interface that allows a purgeable PixelRef (such as a
diff --git a/src/lazy/SkDiscardableMemoryPool.cpp b/src/lazy/SkDiscardableMemoryPool.cpp
index a02f73c..6c13951 100644
--- a/src/lazy/SkDiscardableMemoryPool.cpp
+++ b/src/lazy/SkDiscardableMemoryPool.cpp
@@ -265,8 +265,4 @@
     return global.get();
 }
 
-// defined in SkImageGenerator.h
-void SkPurgeGlobalDiscardableMemoryPool() {
-    SkGetGlobalDiscardableMemoryPool()->dumpPool();
-}
 ////////////////////////////////////////////////////////////////////////////////