VR: Re-target intents not obviously intended for VR back to 2D launcher

Some apps roll their own intent dispatching code, and their intent
dispatching code is incorrect, so they end up erroneously firing 2D
intents explicitly to the VR launcher.

If either the intent doesn't have the Daydream category, or the system
isn't in a VR session (meaning launchInVr definitely wasn't used),
retarget the intent back to the 2D launcher.

Tested on a local Chrome dev build, verified it fixes b/78239314 too.

Bug: 836209
Change-Id: I779c7bf3820ddd50650eb6752d720246a86d24b1
Reviewed-on: https://chromium-review.googlesource.com/1028572
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Reviewed-by: Biao She <bshe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553775}

chrome/android/java/src/org/chromium/chrome/browser/vr/VrMainActivity.java

@@ -12,6 +12,7 @@ import android.os.Bundle;
 
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ApplicationStatus;
+import org.chromium.base.Log;
 import org.chromium.base.TraceEvent;
 import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.LaunchIntentDispatcher;
@@ -34,21 +35,30 @@ import java.lang.ref.WeakReference;
  * intent we don't yet want to fire.
  */
 public class VrMainActivity extends Activity {
+    private static final String TAG = "VrMainActivity";
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         TraceEvent.begin("VrMainActivity.onCreate");
         try {
             super.onCreate(savedInstanceState);
 
-            // TODO(mthiesse, https://crbug.com/831175): Support WebVR launches on standalone VR
-            // devices.
-            if (!VrShellDelegate.deviceSupportsVrLaunches()) {
-                // If the device doesn't support VR launches, forward the intent back to the 2D
-                // launcher. We should only get here on standalone VR devices, or from bad intents
-                // probably sent by testers.
+            boolean hasDaydreamCategory = getIntent().hasCategory(VrIntentUtils.DAYDREAM_CATEGORY);
+
+            if (!VrShellDelegate.deviceSupportsVrLaunches()
+                    || (!hasDaydreamCategory && !VrShellDelegate.isInVrSession())) {
+                StringBuilder error = new StringBuilder("Attempted to launch Chrome into VR ");
+                if (!VrShellDelegate.deviceSupportsVrLaunches()) {
+                    error.append("on a device that doesn't support Chrome in VR.");
+                } else {
+                    error.append("without first being in a VR session or supplying the Daydream "
+                            + "category. Did you mean to use DaydreamApi#launchInVr()?");
+                }
+                Log.e(TAG, error.toString());
+
+                // Remove VR flags and re-target back to the 2D launcher.
                 VrIntentUtils.removeVrExtras(getIntent());
-                getIntent().setComponent(null);
-                getIntent().setPackage(getPackageName());
+                getIntent().setClass(this, ChromeLauncherActivity.class);
 
                 // Daydream drops the MAIN action for unknown reasons...
                 if (getIntent().getAction() == null) getIntent().setAction(Intent.ACTION_MAIN);