Swap to foreground tab when following links that open in a new tab/window in VR Shell.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
index 70f379bce05c66a8ba887faf2c87da37fdb9eb89..835a3c637d386d058471b04f2a15eedbec09cd77 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
@@ -30,6 +30,8 @@ import org.chromium.chrome.browser.multiwindow.MultiWindowUtils;
 import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.TabObserver;
+import org.chromium.chrome.browser.tabmodel.EmptyTabModelSelectorObserver;
+import org.chromium.chrome.browser.tabmodel.TabModelSelectorObserver;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -74,6 +76,7 @@ public class VrShellDelegate {
 
     private final ChromeTabbedActivity mActivity;
     private TabObserver mTabObserver;
+    private TabModelSelectorObserver mTabModelSelectorObserver;
     private Intent mEnterVRIntent;
 
     @VrSupportLevel
@@ -111,6 +114,7 @@ public class VrShellDelegate {
             mVrSupportLevel = VR_NOT_AVAILABLE;
             mEnterVRIntent = null;
             mTabObserver = null;
+            mTabModelSelectorObserver = null;
             return;
         }
 
@@ -147,6 +151,14 @@ public class VrShellDelegate {
                 }
             };
         }
+        if (mTabModelSelectorObserver == null) {
+            mTabModelSelectorObserver = new EmptyTabModelSelectorObserver() {
+                @Override
+                public void onChange() {
+                    swapToForegroundTab();
+                }
+            };
+        }
 
         mVrSupportLevel = mVrDaydreamApi.isDaydreamReadyDevice() ? VR_DAYDREAM : VR_CARDBOARD;
     }
@@ -250,6 +262,7 @@ public class VrShellDelegate {
         mVrShell.resume();
         mTab.updateFullscreenEnabledState();
         setEnterVRResult(true, requestedWebVR);
+        mActivity.getTabModelSelector().addObserver(mTabModelSelectorObserver);
     }
 
     private void setEnterVRResult(boolean success, boolean requestedWebVR) {
@@ -260,6 +273,22 @@ public class VrShellDelegate {
         mRequestedWebVR = false;
     }
 
+    private void swapToForegroundTab() {
+        Tab tab = mActivity.getActivityTab();
+        if (tab == mTab) return;
+        if (!canEnterVR(tab)) {
+            forceExitVr();
+            return;
+        }
+        mTab.removeObserver(mTabObserver);
+        mTab.updateFullscreenEnabledState();
+
+        mVrShell.swapTab(tab);
+        mTab = tab;
+        mTab.addObserver(mTabObserver);
+        mTab.updateFullscreenEnabledState();
+    }
+
     private boolean canEnterVR(Tab tab) {
         if (!LibraryLoader.isInitialized()) {
             return false;
@@ -511,6 +540,7 @@ public class VrShellDelegate {
             mVrClassesWrapper.setVrModeEnabled(false);
             mLastVRExit = SystemClock.uptimeMillis();
         }
+        mActivity.getTabModelSelector().removeObserver(mTabModelSelectorObserver);
         mActivity.setRequestedOrientation(mRestoreOrientation);
         mVrShell.pause();
         removeVrViews();