Docs: Updates Javadoc documentation. Bug: 32532540

am: 2a3ebadcbe

Change-Id: Ibee55c5e73d9b51e5f5df24be01b0b797fa8a7a5

core/java/android/app/ActivityManager.java

@@ -75,7 +75,39 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * Interact with the overall activities running in the system.
+ * <p>
+ * This class gives information about, and interacts
+ * with, activities, services, and the containing
+ * process.
+ * </p>
+ *
+ * <p>
+ * A number of the methods in this class are for
+ * debugging or informational purposes and they should
+ * not be used to affect any runtime behavior of
+ * your app. These methods are called out as such in
+ * the method level documentation.
+ * </p>
+ *
+ *<p>
+ * Most application developers should not have the need to
+ * use this class, most of whose methods are for specialized
+ * use cases. However, a few methods are more broadly applicable.
+ * For instance, {@link android.app.ActivityManager#isLowRamDevice() isLowRamDevice()}
+ * enables your app to detect whether it is running on a low-memory device,
+ * and behave accordingly.
+ * {@link android.app.ActivityManager#clearApplicationUserData() clearApplicationUserData()}
+ * is for apps with reset-data functionality.
+ * </p>
+ *
+ * <p>
+ * In some special use cases, where an app interacts with
+ * its Task stack, the app may use the
+ * {@link android.app.ActivityManager.AppTask} and
+ * {@link android.app.ActivityManager.RecentTaskInfo} inner
+ * classes. However, in general, the methods in this class should
+ * be used for testing and debugging purposes only.
+ * </p>
  */
 public class ActivityManager {
     private static String TAG = "ActivityManager";