PolicyManager: Convert EvalStatus to a enum class.

This simple patch converts EvalStatus to a enum class to have better
type checking over the enum and group the constants on a namespace.

BUG=chromium:340871
TEST=Build and run unit tests.

Change-Id: I56e8d52325c5de578a6c78c7c85c9dccf61d48a1
Reviewed-on: https://chromium-review.googlesource.com/189635
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
diff --git a/policy_manager/policy_manager_unittest.cc b/policy_manager/policy_manager_unittest.cc
index ba001c9..b9253d3 100644
--- a/policy_manager/policy_manager_unittest.cc
+++ b/policy_manager/policy_manager_unittest.cc
@@ -39,7 +39,7 @@
                                         string* error,
                                         bool* result) const {
     *error = "FailingPolicy failed.";
-    return EvalStatusFailed;
+    return EvalStatus::kFailed;
   }
 };
 
@@ -48,14 +48,14 @@
   virtual EvalStatus UpdateCheckAllowed(EvaluationContext* ec, State* state,
                                         string* error,
                                         bool* result) const {
-    return EvalStatusAskMeAgainLater;
+    return EvalStatus::kAskMeAgainLater;
   }
 };
 
 TEST_F(PmPolicyManagerTest, PolicyRequestCall) {
   bool result;
   EvalStatus status = pmut_.PolicyRequest(&Policy::UpdateCheckAllowed, &result);
-  EXPECT_EQ(status, EvalStatusSucceeded);
+  EXPECT_EQ(status, EvalStatus::kSucceeded);
 }
 
 TEST_F(PmPolicyManagerTest, PolicyRequestCallsPolicy) {
@@ -65,9 +65,9 @@
 
   // Tests that the method is called on the policy_ instance.
   EXPECT_CALL(*policy, UpdateCheckAllowed(_, _, _, _))
-      .WillOnce(Return(EvalStatusSucceeded));
+      .WillOnce(Return(EvalStatus::kSucceeded));
   EvalStatus status = pmut_.PolicyRequest(&Policy::UpdateCheckAllowed, &result);
-  EXPECT_EQ(status, EvalStatusSucceeded);
+  EXPECT_EQ(status, EvalStatus::kSucceeded);
 }
 
 TEST_F(PmPolicyManagerTest, PolicyRequestCallsDefaultOnError) {
@@ -77,7 +77,7 @@
   // which will set this as true.
   bool result = false;
   EvalStatus status = pmut_.PolicyRequest(&Policy::UpdateCheckAllowed, &result);
-  EXPECT_EQ(status, EvalStatusSucceeded);
+  EXPECT_EQ(status, EvalStatus::kSucceeded);
   EXPECT_TRUE(result);
 }
 
@@ -86,7 +86,7 @@
   bool result;
 
   EvalStatus status = pmut_.PolicyRequest(&Policy::UpdateCheckAllowed, &result);
-  EXPECT_EQ(status, EvalStatusAskMeAgainLater);
+  EXPECT_EQ(status, EvalStatus::kAskMeAgainLater);
 }
 
 }  // namespace chromeos_policy_manager