[components/policy] Use ThreadTaskRunnerHandle instead of LoopProxy

components/policy/core/common/async_policy_provider.h

Index: components/policy/core/common/async_policy_provider.h
diff --git a/components/policy/core/common/async_policy_provider.h b/components/policy/core/common/async_policy_provider.h
index 63e33865e9c2c061ed9f7422d9fef30525b8f1ee..f2e63687beb943ec823edc33555c44c4dcd9ab94 100644
--- a/components/policy/core/common/async_policy_provider.h
+++ b/components/policy/core/common/async_policy_provider.h
@@ -14,7 +14,7 @@
 #include "components/policy/policy_export.h"
 
 namespace base {
-class MessageLoopProxy;
+class SingleThreadTaskRunner;
 }
 
 namespace policy {
@@ -50,11 +50,12 @@ class POLICY_EXPORT AsyncPolicyProvider : public ConfigurationPolicyProvider,
 
   // Callback passed to the loader that it uses to pass back the current policy
   // bundle to the provider. This is invoked on the background thread and
-  // forwards to OnLoaderReloaded() on the loop that owns the provider,
+  // forwards to OnLoaderReloaded() on the runner that owns the provider,
   // if |weak_this| is still valid.
-  static void LoaderUpdateCallback(scoped_refptr<base::MessageLoopProxy> loop,
-                                   base::WeakPtr<AsyncPolicyProvider> weak_this,
-                                   scoped_ptr<PolicyBundle> bundle);
+  static void LoaderUpdateCallback(
+                  scoped_refptr<base::SingleThreadTaskRunner> runner,
+                  base::WeakPtr<AsyncPolicyProvider> weak_this,
+                  scoped_ptr<PolicyBundle> bundle);
 
   // The |loader_| that does the platform-specific policy loading. It lives
   // on the background thread but is owned by |this|.