Prepare base/ for compilation with OS X 10.7 deployment target.

Disable deprecation warnings for AuthorizationExecuteWithPrivileges, which has
been deprecated since OS X 10.7.

Update the forward declaration of -[NSEvent stage] to have the appropriate
semantics. It was introduced in OS X 10.10.3.

BUG=592663, 593133

Review URL: https://codereview.chromium.org/1773303002

Cr-Commit-Position: refs/heads/master@{#379969}
diff --git a/base/mac/authorization_util.mm b/base/mac/authorization_util.mm
index d09b95d..a459bbf 100644
--- a/base/mac/authorization_util.mm
+++ b/base/mac/authorization_util.mm
@@ -108,6 +108,9 @@
     pipe_pointer = &local_pipe;
   }
 
+// Deprecated in OS X 10.7. https://crbug.com/592663.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   // AuthorizationExecuteWithPrivileges wants |char* const*| for |arguments|,
   // but it doesn't actually modify the arguments, and that type is kind of
   // silly and callers probably aren't dealing with that.  Put the cast here
@@ -117,6 +120,7 @@
                                                        options,
                                                        (char* const*)arguments,
                                                        pipe_pointer);
+#pragma clang diagnostic pop
   if (status != errAuthorizationSuccess) {
     return status;
   }