Add CONTENT_EXPORT_PRIVATE macro

content/common/content_export.h

Index: content/common/content_export.h
diff --git a/content/common/content_export.h b/content/common/content_export.h
index 7e4c79dc9e49a28cb3544ecbeabaca42bdfe1a2c..8c041412b2295f3cab43258c4370a2b9e279cfc4 100644
--- a/content/common/content_export.h
+++ b/content/common/content_export.h
@@ -6,25 +6,35 @@
 #define CONTENT_COMMON_CONTENT_EXPORT_H_
 #pragma once
 
+// Defines CONTENT_EXPORT so that functionality implemented by the content
+// module can be exported to embedders, and CONTENT_EXPORT_PRIVATE that allows
+// unit tests to access features not intended to be used directly by real
+// embedders.
+
 #if defined(COMPONENT_BUILD) && !defined(COMPILE_CONTENT_STATICALLY)
 #if defined(WIN32)
 
 #if defined(CONTENT_IMPLEMENTATION)
 #define CONTENT_EXPORT __declspec(dllexport)
+#define CONTENT_EXPORT_PRIVATE __declspec(dllexport)
 #else
 #define CONTENT_EXPORT __declspec(dllimport)
+#define CONTENT_EXPORT_PRIVATE __declspec(dllimport)
 #endif  // defined(CONTENT_IMPLEMENTATION)
 
 #else // defined(WIN32)
 #if defined(CONTENT_IMPLEMENTATION)
 #define CONTENT_EXPORT __attribute__((visibility("default")))
+#define CONTENT_EXPORT_PRIVATE __attribute__((visibility("default")))
 #else
 #define CONTENT_EXPORT
+#define CONTENT_EXPORT_PRIVATE
 #endif
 #endif
 
 #else // defined(COMPONENT_BUILD)
 #define CONTENT_EXPORT
+#define CONTENT_EXPORT_PRIVATE
 #endif
 
 #endif  // CONTENT_COMMON_CONTENT_EXPORT_H_