Removed the unnecessary passing of the title and description back into the ViewModel from the Fragment (android#358)

The AddEditTaskViewModel already contains the title and description of
the task. In order to be a more accurate example and depict exactly
where the information lives and flows, the title and description is now
just obtained from the ViewModel itself instead of being passed through
from the Fragment.

Author: riggaroo

todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskFragment.java

@@ -108,7 +108,7 @@ private void setupFab() {
         fab.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                mViewModel.saveTask(mViewModel.title.get(), mViewModel.description.get());
+                mViewModel.saveTask();
             }
         });
     }

todoapp/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModel.java

@@ -105,16 +105,16 @@ public void onDataNotAvailable() {
     }
 
     // Called when clicking on fab.
-    void saveTask(String title, String description) {
-        Task task = new Task(title, description);
+    void saveTask() {
+        Task task = new Task(title.get(), description.get());
         if (task.isEmpty()) {
             mSnackbarText.setValue(R.string.empty_task_message);
             return;
         }
         if (isNewTask() || mTaskId == null) {
             createTask(task);
         } else {
-            task = new Task(title, description, mTaskId, mTaskCompleted);
+            task = new Task(title.get(), description.get(), mTaskId, mTaskCompleted);
             updateTask(task);
         }
     }

todoapp/app/src/test/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModelTest.java

@@ -74,7 +74,9 @@ public void setupAddEditTaskViewModel() {
     @Test
     public void saveNewTaskToRepository_showsSuccessMessageUi() {
         // When the ViewModel is asked to save a task
-        mAddEditTaskViewModel.saveTask("New Task Title", "Some Task Description");
+        mAddEditTaskViewModel.description.set("Some Task Description");
+        mAddEditTaskViewModel.title.set("New Task Title");
+        mAddEditTaskViewModel.saveTask();
 
         // Then a task is saved in the repository and the view updated
         verify(mTasksRepository).saveTask(any(Task.class)); // saved to the model