Mac: Use Mavericks occlusion APIs for power savings.

base/mac/sdk_forward_declarations.mm

Index: base/mac/sdk_forward_declarations.mm
diff --git a/base/mac/sdk_forward_declarations.mm b/base/mac/sdk_forward_declarations.mm
index 8f774222aea8d7af34df928c65b3ca8bc953c818..8aea95f36739338315e67c9f385430588410c243 100644
--- a/base/mac/sdk_forward_declarations.mm
+++ b/base/mac/sdk_forward_declarations.mm
@@ -22,6 +22,15 @@ NSString* const NSWindowDidExitFullScreenNotification =
 
 #endif  // MAC_OS_X_VERSION_10_7
 
+// Replicate specific 10.9 SDK declarations for building with prior SDKs.
+#if !defined(MAC_OS_X_VERSION_10_9) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_9
+
+NSString* const NSWindowDidChangeOcclusionStateNotification =
+    @"NSWindowDidChangeOcclusionStateNotification";
+
+#endif  // MAC_OS_X_VERSION_10_9
+
 // Replicate specific 10.10 SDK declarations for building with prior SDKs.
 #if !defined(MAC_OS_X_VERSION_10_10) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_10