Reland of land "Turn libbase into a component"

src/base/platform/mutex.h

Index: src/base/platform/mutex.h
diff --git a/src/base/platform/mutex.h b/src/base/platform/mutex.h
index 61df19d66a514ec65987ed9b0ec4e11d67a27425..e7231bdd9ec91bf019b19e96e3a2b9d7d440f08f 100644
--- a/src/base/platform/mutex.h
+++ b/src/base/platform/mutex.h
@@ -5,6 +5,7 @@
 #ifndef V8_BASE_PLATFORM_MUTEX_H_
 #define V8_BASE_PLATFORM_MUTEX_H_
 
+#include "src/base/base-export.h"
 #include "src/base/lazy-instance.h"
 #if V8_OS_WIN
 #include "src/base/win32-headers.h"
@@ -33,7 +34,7 @@
 // |TryLock()|. The behavior of a program is undefined if a mutex is destroyed
 // while still owned by some thread. The Mutex class is non-copyable.
 
-class Mutex final {
+class V8_BASE_EXPORT Mutex final {
  public:
   Mutex();
   ~Mutex();
@@ -127,7 +128,7 @@
 // The behavior of a program is undefined if a recursive mutex is destroyed
 // while still owned by some thread. The RecursiveMutex class is non-copyable.
 
-class RecursiveMutex final {
+class V8_BASE_EXPORT RecursiveMutex final {
  public:
   RecursiveMutex();
   ~RecursiveMutex();