Bug 1564846 - Do better at managing secondary windows in TestRunnerActivity r=kats

Differential Revision: https://phabricator.services.mozilla.com/D37570

--HG--
extra : moz-landing-system : lando

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/TestRunnerActivity.java

@@ -41,7 +41,35 @@ public class TestRunnerActivity extends Activity {
     private GeckoView mView;
     private boolean mKillProcessOnDestroy;
 
-    private HashMap<GeckoSession, GeckoDisplay> mDisplays = new HashMap<>();
+    private HashMap<GeckoSession, Display> mDisplays = new HashMap<>();
+
+    private static class Display {
+        public final SurfaceTexture texture;
+        public final Surface surface;
+
+        private final int width;
+        private final int height;
+        private GeckoDisplay sessionDisplay;
+
+        public Display(final int width, final int height) {
+            this.width = width;
+            this.height = height;
+            texture = new SurfaceTexture(0);
+            texture.setDefaultBufferSize(width, height);
+            surface = new Surface(texture);
+        }
+
+        public void attach(final GeckoSession session) {
+            sessionDisplay = session.acquireDisplay();
+            sessionDisplay.surfaceChanged(surface, width, height);
+        }
+
+        public void release(final GeckoSession session) {
+            sessionDisplay.surfaceDestroyed();
+            session.releaseDisplay(sessionDisplay);
+        }
+    }
+
     private HashSet<GeckoSession> mOwnedSessions = new HashSet<>();
 
     private GeckoSession.PermissionDelegate mPermissionDelegate = new GeckoSession.PermissionDelegate() {
@@ -158,11 +186,9 @@ public class TestRunnerActivity extends Activity {
     private GeckoSession createBackgroundSession(final GeckoSessionSettings settings) {
         final GeckoSession session = createSession(settings);
 
-        final SurfaceTexture texture  = new SurfaceTexture(0);
-        final Surface surface = new Surface(texture);
+        final Display display = new Display(mView.getWidth(), mView.getHeight());
+        display.attach(session);
 
-        final GeckoDisplay display = session.acquireDisplay();
-        display.surfaceChanged(surface, mView.getWidth(), mView.getHeight());
         mDisplays.put(session, display);
 
         return session;
@@ -170,10 +196,8 @@ public class TestRunnerActivity extends Activity {
 
     private void closeSession(GeckoSession session) {
         if (mDisplays.containsKey(session)) {
-            final GeckoDisplay display = mDisplays.remove(session);
-            display.surfaceDestroyed();
-
-            session.releaseDisplay(display);
+            final Display display = mDisplays.remove(session);
+            display.release(session);
         }
         mOwnedSessions.remove(session);
         session.close();