audio policy: fix virtual called from constructor

Call initialize() after constructing AudioPolicyManager
from factory to avoid calling virtual methods from constructor.

Bug: 136491567
Test: make
Change-Id: Ie0b591d90e643b1fd1c326f9731dc656b38230dc
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.h b/services/audiopolicy/managerdefault/AudioPolicyManager.h
index d88d1ec..5f651cc 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.h
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.h
@@ -307,6 +307,8 @@
             return volumeGroup != VOLUME_GROUP_NONE ? NO_ERROR : BAD_VALUE;
         }
 
+        status_t initialize();
+
 protected:
         // A constructor that allows more fine-grained control over initialization process,
         // used in automatic tests.
@@ -321,7 +323,6 @@
         //   - initialize.
         AudioPolicyConfig& getConfig() { return mConfig; }
         void loadConfig();
-        status_t initialize();
 
         // From AudioPolicyManagerObserver
         virtual const AudioPatchCollection &getAudioPatches() const