remove SkPurgeGlobalDiscardableMemoryPool

src/lazy/SkDiscardableMemoryPool.cpp

Index: src/lazy/SkDiscardableMemoryPool.cpp
diff --git a/src/lazy/SkDiscardableMemoryPool.cpp b/src/lazy/SkDiscardableMemoryPool.cpp
index a02f73c93829578c54844b1cf842bdb5e4f6c7b0..6c13951aa865938e953e549b4b5ada78834e674c 100644
--- a/src/lazy/SkDiscardableMemoryPool.cpp
+++ b/src/lazy/SkDiscardableMemoryPool.cpp
@@ -265,8 +265,4 @@ SkDiscardableMemoryPool* SkGetGlobalDiscardableMemoryPool() {
     return global.get();
 }
 
-// defined in SkImageGenerator.h
-void SkPurgeGlobalDiscardableMemoryPool() {
-    SkGetGlobalDiscardableMemoryPool()->dumpPool();
-}
 ////////////////////////////////////////////////////////////////////////////////