tools/gn/example: Fix the usage of HELLO_SHARED_IMPLEMENTATION.

HELLO_IMPLEMENTATION was a typo in the no-win condition.

The correct is to check if HELLO_SHARED_IMPLEMENTATION was defined,
as that is what is defined by //tools/gn/example:hello_shared target.

BUG=None
TBR=brettw@chromium.org

Review URL: https://codereview.chromium.org/966333006

Cr-Commit-Position: refs/heads/master@{#318695}

tools/gn/example/hello_shared.h

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef HELLO_SHARED_H_
-#define HELLO_SHARED_H_
+#ifndef TOOLS_GN_EXAMPLE_HELLO_SHARED_H_
+#define TOOLS_GN_EXAMPLE_HELLO_SHARED_H_
 
 #if defined(WIN32)
 
@@ -17,16 +17,16 @@
 
 #else
 
-#if defined(HELLO_IMPLEMENTATION)
+#if defined(HELLO_SHARED_IMPLEMENTATION)
 #define HELLO_EXPORT __attribute__((visibility("default")))
 #define HELLO_EXPORT_PRIVATE __attribute__((visibility("default")))
 #else
 #define HELLO_EXPORT
 #define HELLO_EXPORT_PRIVATE
-#endif  // defined(HELLO_IMPLEMENTATION)
+#endif  // defined(HELLO_SHARED_IMPLEMENTATION)
 
 #endif
 
 HELLO_EXPORT const char* GetSharedText();
 
-#endif  // HELLO_SHARED_H_
+#endif  // TOOLS_GN_EXAMPLE_HELLO_SHARED_H_

tools/gn/example/hello_static.h

@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef HELLO_STATIC_H_
-#define HELLO_STATIC_H_
+#ifndef TOOLS_GN_EXAMPLE_HELLO_STATIC_H_
+#define TOOLS_GN_EXAMPLE_HELLO_STATIC_H_
 
 const char* GetStaticText();
 
-#endif  // HELLO_STATIC_H_
+#endif  // TOOLS_GN_EXAMPLE_HELLO_STATIC_H_