Clean up a few includes, introduce iwyu.

include/core/SkTypes.h

Index: include/core/SkTypes.h
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index 1b0b12c621c6ce3ef282239959e0ec15e61c1f2e..f703af467c8bb195b3b9db4b4eec3f721aaacf92 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -8,6 +8,7 @@
 #ifndef SkTypes_DEFINED
 #define SkTypes_DEFINED
 
+// IWYU pragma: begin_exports
 #include "SkPreConfig.h"
 #include "SkUserConfig.h"
 #include "SkPostConfig.h"
@@ -19,6 +20,10 @@
 #elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
     #include <immintrin.h>
 #endif
+// IWYU pragma: end_exports
+
+#include <stdlib.h>

[reed1, 2015/07/29 14:40:39]

just curious: what do these two bring us that we use?

[bungeman-skia, 2015/07/29 16:46:23]

stdlib: Nothing in SkTypes needs this, and most files don't, but at least
SkGraphics.cpp, SkParse.cpp, SkRTCont.cpp, SkResourceCache.cpp, and
SkRegion_path.cpp (for qsort!?) currently depend on this being here to provide
various declarations.

string.h: memset below, and I think some files are depending on it for various
things, I haven't looked too hard at this one yet.

+#include <string.h>
 
 /** \file SkTypes.h
 */