IWYU to fix an odd inclusion of SkMalloc.h inside SkTypes.h

Bug: 
Change-Id: Ife8c994a3874f74d00143761db4b2ac613a6cd10
Reviewed-on: https://chromium-review.googlesource.com/850920Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527070}

skia/ext/SkMemory_new_handler.cpp

@@ -8,6 +8,7 @@
 #include "base/process/memory.h"
 #include "build/build_config.h"
 #include "third_party/skia/include/core/SkTypes.h"
+#include "third_party/skia/include/private/SkMalloc.h"
 
 #if defined(OS_WIN)
 #include <windows.h>