Export some unix-specific content symbols

content/browser/zygote_host_linux.h

Index: content/browser/zygote_host_linux.h
diff --git a/content/browser/zygote_host_linux.h b/content/browser/zygote_host_linux.h
index facabbb5f38113f9202bc6eaec339fc3816c68f2..e655b6ee4a2d0562724ea71c1ef6ca8f28ccfe8f 100644
--- a/content/browser/zygote_host_linux.h
+++ b/content/browser/zygote_host_linux.h
@@ -15,6 +15,7 @@
 #include "base/process.h"
 #include "base/process_util.h"
 #include "base/synchronization/lock.h"
+#include "content/common/content_export.h"
 
 template<typename Type>
 struct DefaultSingletonTraits;
@@ -25,7 +26,7 @@ static const char kZygoteMagic[] = "ZYGOTE_OK";
 
 // The zygote host is the interface, in the browser process, to the zygote
 // process.
-class ZygoteHost {
+class CONTENT_EXPORT ZygoteHost {
  public:
   // Returns the singleton instance.
   static ZygoteHost* GetInstance();