Adjust Context Hub AIDL based on feedback

- Add additional documentation of ContextHubMessage.aidl.
- Remove redundant TYPE_ specifier in HostEndpointInfo.aidl.

Bug: 213474931
Test: Compile
Change-Id: Ice1ac925a8b977abee8a9fa376ad40b33f315a3f

contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/HostEndpointInfo.aidl

@@ -40,7 +40,7 @@ parcelable HostEndpointInfo {
   @nullable String attributionTag;
   @Backing(type="int") @VintfStability
   enum Type {
-    TYPE_FRAMEWORK = 1,
-    TYPE_APP = 2,
+    FRAMEWORK = 1,
+    APP = 2,
   }
 }

contexthub/aidl/android/hardware/contexthub/ContextHubMessage.aidl

@@ -32,10 +32,14 @@ parcelable ContextHubMessage {
      */
     char hostEndPoint;
 
-    /** The type of this message */
+    /**
+     * The type of this message payload, defined by the communication endpoints (i.e.
+     * either the nanoapp or the host endpoint). This value can be used to distinguish
+     * the handling of messageBody (e.g. for decoding).
+     */
     int messageType;
 
-    /** The payload containing the message */
+    /** The payload containing the message. */
     byte[] messageBody;
 
     /**

contexthub/aidl/android/hardware/contexthub/HostEndpointInfo.aidl

@@ -37,12 +37,12 @@ parcelable HostEndpointInfo {
     @Backing(type="int")
     enum Type {
         /**
-           This endpoint is from the Android framework, where packageName and attributionTag may be
-           empty.
+         * This endpoint is from the Android framework, where packageName and attributionTag may be
+         * empty.
          */
-        TYPE_FRAMEWORK = 1,
+        FRAMEWORK = 1,
 
         /** This endpoint is an Android app. */
-        TYPE_APP = 2,
+        APP = 2,
     }
 }