Show indefinite progress bar (circular type) while the VM is booting

... and remove the toast

Bug: N/A
Test: run Terminal app
Change-Id: I2b01e43d184ee8dfad0a7e753ac44fd5c85a54cf
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
index bd35f51..612da12 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
@@ -388,7 +388,6 @@
     }
 
     private void startVm() {
-        Toast.makeText(this, R.string.vm_creation_message, Toast.LENGTH_SHORT).show();
         android.os.Trace.beginAsyncSection("executeTerminal", 0);
         VmLauncherServices.startVmLauncherService(this, this);
     }
diff --git a/android/TerminalApp/res/layout/activity_headless.xml b/android/TerminalApp/res/layout/activity_headless.xml
index 736b45a..9211799 100644
--- a/android/TerminalApp/res/layout/activity_headless.xml
+++ b/android/TerminalApp/res/layout/activity_headless.xml
@@ -12,15 +12,31 @@
         android:layout_width="match_parent"
         android:layout_height="?attr/actionBarSize"
         app:layout_constraintTop_toTopOf="parent"/>
-    <TextView
-        android:id="@+id/ip_addr_textview"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content" />
-  <WebView
-      android:id="@+id/webview"
-      android:layout_width="match_parent"
-      android:layout_height="match_parent"
-      android:layout_marginBottom="5dp"
-      android:visibility="invisible"/>
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+        <LinearLayout
+            android:orientation="vertical"
+            android:gravity="center"
+            android:layout_gravity="center"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content">
+            <TextView
+                android:text="@string/vm_creation_message"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginBottom="5dp"/>
+            <ProgressBar
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"/>
+        </LinearLayout>
+        <WebView
+            android:id="@+id/webview"
+            android:layout_marginBottom="5dp"
+            android:layout_gravity="fill"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:visibility="invisible"/>
+    </FrameLayout>
 
 </LinearLayout>