Make mojo::Callback<>::Runnable::Run non-const.

chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc

Index: chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc
diff --git a/chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc b/chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc
index ae0ead1da91c4bef64ee6c2eff39c2595fc46d83..7e7eab60cb554896866afe4ee7246335e6533661 100644
--- a/chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc
+++ b/chrome/browser/chromeos/arc/arc_policy_bridge_unittest.cc
@@ -41,7 +41,7 @@ class ArcPolicyBridgeTest : public testing::Test {
    public:
     explicit PolicyStringRunnable(mojo::String expected)
         : expected_(expected) {}
-    void Run(const mojo::String& policies) const override {
+    void Run(const mojo::String& policies) override {
       EXPECT_EQ(expected_, policies);
     }