Rename API to match StorageStats.

Since they're both measuring app code (APKs), name this API
consistently with StorageStats.getAppBytes().

Bug: 64331226
Test: builds, boots
Change-Id: I1b00427b619a78c043b1b5fac2d0e6406b51d454
diff --git a/core/java/android/net/TrafficStats.java b/core/java/android/net/TrafficStats.java
index 1985707..c339856 100644
--- a/core/java/android/net/TrafficStats.java
+++ b/core/java/android/net/TrafficStats.java
@@ -110,12 +110,12 @@
     public static final int TAG_SYSTEM_RESTORE = 0xFFFFFF04;
 
     /**
-     * Default tag value for code or resources downloaded by an app store on
-     * behalf of the app, such as app updates.
+     * Default tag value for code (typically APKs) downloaded by an app store on
+     * behalf of the app, such as updates.
      *
      * @hide
      */
-    public static final int TAG_SYSTEM_CODE = 0xFFFFFF05;
+    public static final int TAG_SYSTEM_APP = 0xFFFFFF05;
 
     /** @hide */
     public static final int TAG_SYSTEM_DHCP = 0xFFFFFF40;
@@ -213,14 +213,14 @@
     /**
      * Set active tag to use when accounting {@link Socket} traffic originating
      * from the current thread. The tag used internally is well-defined to
-     * distinguish all code-related traffic, such as updates performed by an app
-     * store.
+     * distinguish all code (typically APKs) downloaded by an app store on
+     * behalf of the app, such as updates.
      *
      * @hide
      */
     @SystemApi
-    public static void setThreadStatsTagCode() {
-        setThreadStatsTag(TAG_SYSTEM_CODE);
+    public static void setThreadStatsTagApp() {
+        setThreadStatsTag(TAG_SYSTEM_APP);
     }
 
     /**