Support WebVR on standalone VR devices.

Treat standalones as supporting everything, but when we try to enter
browsing mode, exit VR, dropping to the 2D-in-VR path.

Bug: 803202
Change-Id: I3b4e38b530257179f6351e542951ac0eebb956bd
Reviewed-on: https://chromium-review.googlesource.com/1012922Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551062}

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

@@ -468,7 +468,7 @@ public class VrShellDelegate
         // TODO(mthiesse, crbug.com/791090): Re-enable VR mode for devices that boot to VR once we
         // support those devices.
         VrClassesWrapper wrapper = getVrClassesWrapper();
-        if (wrapper == null || wrapper.bootsToVr() || !isVrCoreCompatible(tabToShowInfobarIn)) {
+        if (wrapper == null || !isVrCoreCompatible(tabToShowInfobarIn)) {
             return VrSupportLevel.VR_NOT_AVAILABLE;
         }
 
@@ -705,7 +705,7 @@ public class VrShellDelegate
      */
     public static void setVrModeEnabled(Activity activity, boolean enabled) {
         VrClassesWrapper wrapper = getVrClassesWrapper();
-        if (wrapper == null || wrapper.bootsToVr()) return;
+        if (wrapper == null) return;
         ensureLifecycleObserverInitialized();
         if (enabled) {
             if (sVrModeEnabledActivitys.contains(activity)) return;
@@ -881,7 +881,7 @@ public class VrShellDelegate
     }
 
     public static boolean deviceSupportsVrLaunches() {
-        return isDaydreamReadyDevice() && !getVrClassesWrapper().bootsToVr();
+        return isDaydreamReadyDevice();
     }
 
     // TODO(mthiesse): Should have package visibility only. We need to unify our vr and vr_shell
@@ -950,7 +950,7 @@ public class VrShellDelegate
      *  @return Whether or not VR is supported on this platform.
      */
     /* package */ static boolean isVrEnabled() {
-        return getVrClassesWrapper() != null && !getVrClassesWrapper().bootsToVr();
+        return getVrClassesWrapper() != null;
     }
 
     private static void addBlackOverlayViewForActivity(ChromeActivity activity) {
@@ -1231,6 +1231,13 @@ public class VrShellDelegate
         // UI which is gone.
         assert !mPaused;
         if (mInVr) return;
+        if (!mRequestedWebVr && !tentativeWebVrMode && !mAutopresentWebVr
+                && getVrClassesWrapper().bootsToVr()) {
+            // We don't support VR browsing on standalone devices, so if we try to enter browsing
+            // mode, just drop back to the 2D-in-VR path.
+            cancelPendingVrEntry();
+            return;
+        }
         if (mNativeVrShellDelegate == 0) {
             cancelPendingVrEntry();
             return;
@@ -1598,6 +1605,12 @@ public class VrShellDelegate
             getVrDaydreamApi().launchVrHomescreen();
             return;
         }
+
+        if (getVrClassesWrapper().bootsToVr()) {
+            shutdownVr(true /* disableVrMode */, true /* stayingInChrome */);
+            return;
+        }
+
         if (!isVrBrowsingEnabled()) {
             if (isDaydreamCurrentViewerInternal()) {
                 getVrDaydreamApi().launchVrHomescreen();