Use source parameter to determine policy priority.

components/policy/core/common/policy_map.cc

Index: components/policy/core/common/policy_map.cc
diff --git a/components/policy/core/common/policy_map.cc b/components/policy/core/common/policy_map.cc
index 9ad2627143cc65469a1060fd3ca6fdd9ac32c000..1814be07e5b9f5af1eeda75bc48d8fd9a221d446 100644
--- a/components/policy/core/common/policy_map.cc
+++ b/components/policy/core/common/policy_map.cc
@@ -37,10 +37,13 @@ PolicyMap::Entry PolicyMap::Entry::DeepCopy() const {
 
 bool PolicyMap::Entry::has_higher_priority_than(
     const PolicyMap::Entry& other) const {
-  if (level == other.level)
+  if (level == other.level) {
+    if (scope == other.scope) {
+      return source > other.source;
+    }
     return scope > other.scope;
-  else
-    return level > other.level;
+  }
+  return level > other.level;
 }
 
 bool PolicyMap::Entry::Equals(const PolicyMap::Entry& other) const {