Bug 1377579 - Add progress bar to GeckoView-based custom tabs. r=snorp

mobile/android/app/src/main/res/layout/customtabs_activity.xml

@@ -27,6 +27,16 @@
         android:layout_height="match_parent"
         android:scrollbars="none"/>
 
+    <ProgressBar
+        android:id="@id/page_progress"
+        style="@style/Base.Widget.AppCompat.ProgressBar.Horizontal"
+        android:layout_width="match_parent"
+        android:layout_height="4dp"
+        android:layout_alignTop="@id/gecko_view"
+        android:background="@drawable/url_bar_bg"
+        android:progressDrawable="@drawable/progressbar"
+        tools:progress="70"/>
+
     <View android:id="@+id/custom_tabs_doorhanger_overlay"
         android:layout_width="match_parent"
         android:layout_height="match_parent"

mobile/android/base/java/org/mozilla/gecko/customtabs/CustomTabsActivity.java

@@ -28,6 +28,7 @@ import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
+import android.widget.ProgressBar;
 
 import org.mozilla.gecko.ActivityHandlerHelper;
 import org.mozilla.gecko.EventDispatcher;
@@ -61,6 +62,7 @@ public class CustomTabsActivity extends AppCompatActivity
     private GeckoPopupMenu popupMenu;
     private View doorhangerOverlay;
     private ActionBarPresenter actionBarPresenter;
+    private ProgressBar mProgressView;
     // A state to indicate whether this activity is finishing with customize animation
     private boolean usingCustomAnimation = false;
 
@@ -86,6 +88,8 @@ public class CustomTabsActivity extends AppCompatActivity
 
         doorhangerOverlay = findViewById(R.id.custom_tabs_doorhanger_overlay);
 
+        mProgressView = (ProgressBar) findViewById(R.id.page_progress);
+        updateProgress(10);
         final Toolbar toolbar = (Toolbar) findViewById(R.id.actionbar);
         setSupportActionBar(toolbar);
         final ActionBar actionBar = getSupportActionBar();
@@ -388,6 +392,19 @@ public class CustomTabsActivity extends AppCompatActivity
         forwardMenuItem.setEnabled(mCanGoForward);
     }
 
+    /**
+     * Update the state of the progress bar.
+     * @param progress The current loading progress; must be between 0 and 100
+     */
+    private void updateProgress(final int progress) {
+        if (mCanStop) {
+            mProgressView.setVisibility(View.VISIBLE);
+            mProgressView.setProgress(progress);
+        } else {
+            mProgressView.setVisibility(View.GONE);
+        }
+    }
+
     /**
      * Update loading status of current page
      */
@@ -498,6 +515,7 @@ public class CustomTabsActivity extends AppCompatActivity
     public void onLocationChange(GeckoView view, String url) {
         mCurrentUrl = url;
         updateActionBar();
+        updateProgress(60);
     }
 
     @Override
@@ -518,12 +536,14 @@ public class CustomTabsActivity extends AppCompatActivity
         mCanStop = true;
         updateActionBar();
         updateCanStop();
+        updateProgress(20);
     }
 
     @Override
     public void onPageStop(GeckoView view, boolean success) {
         mCanStop = false;
         updateCanStop();
+        updateProgress(100);
     }
 
     @Override