Discard back button presses to exit the app in WaveVR and Daydream

app/src/googlevr/java/org/mozilla/vrbrowser/PlatformActivity.java

@@ -107,19 +107,12 @@ public void onDrawFrame(GL10 gl) {
 
         mLayout.setAsyncReprojectionEnabled(true);
         mLayout.setPresentationView(mView);
-
-        try {
-            final Class flatActivityClass = Class.forName(FLAT_ACTIVITY_CLASSNAME);
-            mLayout.getUiLayout().setCloseButtonListener(new Runnable() {
-                @Override
-                public void run() {
-                    startActivity(new Intent(PlatformActivity.this, flatActivityClass));
-                }
-            });
-        }
-        catch (ClassNotFoundException e) {
-            Log.e(LOGTAG,"Class not found: " + e.toString());
-        }
+        mLayout.getUiLayout().setCloseButtonListener(new Runnable() {
+            @Override
+            public void run() {
+                finish();
+            }
+        });
 
         setImmersiveSticky();
         setContentView(mLayout);
@@ -200,6 +193,13 @@ private void notifyPendingEvents() {
         }
     }
 
+    @Override
+    public void onBackPressed() {
+        // Discard back button presses that would otherwise exit the app,
+        // as the UI standard on this platform is to require the use of
+        // the Daydream button to exit application.
+    }
+
     private native void activityCreated(Object aAssetManager, final long aContext);
     private native void activityPaused();
     private native void activityResumed();

app/src/wavevr/java/org/mozilla/vrbrowser/PlatformActivity.java

@@ -37,6 +37,13 @@ public void run() {
         });
     }
 
+    @Override
+    public void onBackPressed() {
+        // Discard back button presses that would otherwise exit the app,
+        // as the UI standard on this platform is to require the use of
+        // the system menu to exit applications.
+    }
+
     protected native void queueRunnable(Runnable aRunnable);
     protected native void initializeJava(AssetManager aAssets);
 }