Add IsOSElCapitan() and other util functions.

base/mac/mac_util.h

Index: base/mac/mac_util.h
diff --git a/base/mac/mac_util.h b/base/mac/mac_util.h
index f8ffa97545decf3717c102853461d92877f5e8a6..060f35b6c0c6469211956d9f53ada4c6cda1b95d 100644
--- a/base/mac/mac_util.h
+++ b/base/mac/mac_util.h
@@ -147,6 +147,10 @@ BASE_EXPORT bool IsOSMavericksOrLater();
 BASE_EXPORT bool IsOSYosemite();
 BASE_EXPORT bool IsOSYosemiteOrLater();
 
+// El Capitan is Mac OS X 10.11, Darwin 15.
+BASE_EXPORT bool IsOSElCapitan();
+BASE_EXPORT bool IsOSElCapitanOrLater();
+
 // This should be infrequently used. It only makes sense to use this to avoid
 // codepaths that are very likely to break on future (unreleased, untested,
 // unborn) OS releases, or to log when the OS is newer than any known version.
@@ -157,6 +161,7 @@ BASE_EXPORT bool IsOSLaterThanYosemite_DontCallThis();
 inline bool IsOSLionOrEarlier() { return !IsOSMountainLionOrLater(); }
 inline bool IsOSMountainLionOrEarlier() { return !IsOSMavericksOrLater(); }
 inline bool IsOSMavericksOrEarlier() { return !IsOSYosemiteOrLater(); }
+inline bool IsOSYosemiteOrEarlier() { return !IsOSElCapitanOrLater(); }
 
 // When the deployment target is set, the code produced cannot run on earlier
 // OS releases. That enables some of the IsOS* family to be implemented as
@@ -213,6 +218,18 @@ inline bool IsOSYosemite() { return false; }
 inline bool IsOSLaterThanYosemite_DontCallThis() { return true; }
 #endif
 
+#if defined(MAC_OS_X_VERSION_10_11) && \
+    MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_11
+#define BASE_MAC_MAC_UTIL_H_INLINED_GE_10_11
+inline bool IsOSElCapitanOrLater() { return true; }
+#endif
+
+#if defined(MAC_OS_X_VERSION_10_11) && \
+    MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_11
+#define BASE_MAC_MAC_UTIL_H_INLINED_GT_10_11
+inline bool IsOSElCapitan() { return false; }
+#endif
+
 // Retrieve the system's model identifier string from the IOKit registry:
 // for example, "MacPro4,1", "MacBookPro6,1". Returns empty string upon
 // failure.