EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/system/mutex.h

Index: mojo/edk/system/mutex.h
diff --git a/mojo/edk/system/mutex.h b/mojo/edk/system/mutex.h
index a78a16bd839a52b8d12a9f4aa93cb7eeb69934d2..859f6a31a6330a801bc302d8f3accfb559d7fbc9 100644
--- a/mojo/edk/system/mutex.h
+++ b/mojo/edk/system/mutex.h
@@ -14,7 +14,6 @@
 
 #include "base/synchronization/lock_impl.h"
 #include "base/threading/platform_thread.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/edk/system/thread_annotations.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -23,7 +22,7 @@ namespace system {
 
 // Mutex -----------------------------------------------------------------------
 
-class MOJO_LOCKABLE MOJO_SYSTEM_IMPL_EXPORT Mutex {
+class MOJO_LOCKABLE Mutex {
  public:
 #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
   Mutex() : lock_() {}
@@ -73,7 +72,7 @@ class MOJO_LOCKABLE MOJO_SYSTEM_IMPL_EXPORT Mutex {
 
 // MutexLocker -----------------------------------------------------------------
 
-class MOJO_SCOPED_LOCKABLE MOJO_SYSTEM_IMPL_EXPORT MutexLocker {
+class MOJO_SCOPED_LOCKABLE MutexLocker {
  public:
   explicit MutexLocker(Mutex* mutex) MOJO_EXCLUSIVE_LOCK_FUNCTION(mutex)
       : mutex_(mutex) {