Fix the "call to 'abs' is ambiguous" error in line 42

std::abs() for integers is declared in <cstdlib>, not <cmath>

R=pkotwicz@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/278303002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270082 0039d316-1c4b-4281-b951-d872f2087c98

ash/wm/workspace/two_step_edge_cycler.cc

@@ -4,7 +4,7 @@
 
 #include "ash/wm/workspace/two_step_edge_cycler.h"
 
-#include <cmath>
+#include <cstdlib>
 
 namespace ash {
 namespace {