Add code needed to build skia as a windows dll within the chromium project.
- Export/import skia APIs if SKIA_DLL is defined.
- This change has no effect on skia.

Review URL: http://codereview.appspot.com/4282042

git-svn-id: http://skia.googlecode.com/svn/trunk@944 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkPreConfig.h b/include/core/SkPreConfig.h
index f907578..daf2041 100644
--- a/include/core/SkPreConfig.h
+++ b/include/core/SkPreConfig.h
@@ -96,5 +96,21 @@
     #define SK_CPU_HAS_CONDITIONAL_INSTR
 #endif
 
+//////////////////////////////////////////////////////////////////////
+
+#if !defined(SKIA_IMPLEMENTATION)
+    #define SKIA_IMPLEMENTATION 0
+#endif
+ 
+#if defined(WIN32) && defined(SKIA_DLL)
+    #if SKIA_IMPLEMENTATION
+        #define SK_API __declspec(dllexport)
+    #else
+        #define SK_API __declspec(dllimport)
+    #endif
+#else
+    #define SK_API
+#endif
+
 #endif