ShapeDetection: add support for Text Detection in Mac

base/mac/sdk_forward_declarations.h

Index: base/mac/sdk_forward_declarations.h
diff --git a/base/mac/sdk_forward_declarations.h b/base/mac/sdk_forward_declarations.h
index 7ea7829d9afeb38f0fa224317093c04c88012f02..5416c6f94658283c5de4da33c0d83790c7425c7a 100644
--- a/base/mac/sdk_forward_declarations.h
+++ b/base/mac/sdk_forward_declarations.h
@@ -163,6 +163,18 @@ BASE_EXPORT extern NSString* const NSAppearanceNameVibrantLight;
 
 #endif  // MAC_OS_X_VERSION_10_10
 
+// ----------------------------------------------------------------------------
+// Define NSStrings only available in newer versions of the OSX SDK to force
+// them to be statically linked.
+// ----------------------------------------------------------------------------
+
+extern "C" {
+#if !defined(MAC_OS_X_VERSION_10_11) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_11
+BASE_EXPORT extern NSString* const CIDetectorTypeText;
+#endif  // MAC_OS_X_VERSION_10_11
+}  // extern "C"
+
 // Once Chrome no longer supports OSX 10.10, everything within this
 // preprocessor block can be removed.
 #if !defined(MAC_OS_X_VERSION_10_11) || \