export blink::Platform symbols in shared_library builds

third_party/WebKit/public/platform/WebCommon.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 42 matching lines @@
         #if BLINK_PLATFORM_IMPLEMENTATION
             #define BLINK_PLATFORM_EXPORT __declspec(dllexport)
         #else // BLINK_PLATFORM_IMPLEMENTATION
             #define BLINK_PLATFORM_EXPORT __declspec(dllimport)
         #endif
         #if BLINK_COMMON_IMPLEMENTATION
             #define BLINK_COMMON_EXPORT __declspec(dllexport)
         #else // BLINK_COMMON_IMPLEMENTATION
             #define BLINK_COMMON_EXPORT __declspec(dllimport)
         #endif
+        #define BLINK_PLATFORM_HIDDEN

[dcheng, 2016/03/07 04:42:08]

I wouldn't change these macros.

[Mostyn Bramley-Moore, 2016/03/07 06:38:31]

OK.  BTW, the presubmit hooks complain that macros should not be indented-
should I fix that here, or will that be taken care of in a clang-format run
later?

+        #define BLINK_PLATFORM_EXPORT_CLASS
     #else // defined(WIN32)
+        #define BLINK_PLATFORM_HIDDEN __attribute__((visibility("hidden")))
         #define BLINK_EXPORT __attribute__((visibility("default")))
-        #define BLINK_PLATFORM_EXPORT __attribute__((visibility("default")))
-        #define BLINK_COMMON_EXPORT __attribute__((visibility("default")))
+        #define BLINK_PLATFORM_EXPORT BLINK_EXPORT
+        #define BLINK_PLATFORM_EXPORT_CLASS BLINK_EXPORT
+        #define BLINK_COMMON_EXPORT BLINK_EXPORT
     #endif
 #else // defined(COMPONENT_BUILD)
     #define BLINK_EXPORT
     #define BLINK_PLATFORM_EXPORT
+    #define BLINK_PLATFORM_EXPORT_CLASS
+    #define BLINK_PLATFORM_HIDDEN
     #define BLINK_COMMON_EXPORT
 #endif
 
 
 // -----------------------------------------------------------------------------
 // Basic types
 
 #include <stddef.h> // For size_t
 #include <stdint.h> // For int32_t
 
@@ skipping 25 matching lines @@
 #else
 #define BLINK_ASSERT(assertion) do { \
     if (!(assertion)) \
         failedAssertion(__FILE__, __LINE__, __FUNCTION__, #assertion); \
 } while (0)
 #endif
 
 #define BLINK_ASSERT_NOT_REACHED() BLINK_ASSERT(0)
 
 #endif