VR: Use isInVrSession API to keep Chrome in VR until user has left VR

This fixes the Daydream Dashboard issues so that if Chrome is simply
stopped/started in VR without any intents, Chrome stays in VR.

Also makes resuming Chrome from DD home way faster if Chrome was
already in VR.

Bug: 780887
Change-Id: Iab7f713bfc5b85972f908ea141e3b495297d7286
Reviewed-on: https://chromium-review.googlesource.com/944547Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540403}

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

@@ -77,6 +77,12 @@ public interface VrDaydreamApi {
      */
     Intent setupVrIntent(Intent intent);
 
+    /**
+     * Whether the user is currently in a VR session. Note that this should be treated as heuristic,
+     * and may at times be wrong.
+     */
+    boolean isInVrSession();
+
     /**
      * Closes this DaydreamApi instance.
      */

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

@@ -134,6 +134,11 @@ public class VrDaydreamApiImpl implements VrDaydreamApi {
         return DaydreamApi.setupVrIntent(intent);
     }
 
+    @Override
+    public boolean isInVrSession() {
+        return DaydreamApi.isInVrSession(mContext);
+    }
+
     @Override
     public void close() {
         if (mDaydreamApi == null) return;

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

@@ -971,16 +971,16 @@ public class VrShellDelegate
     }
 
     private void onVrIntent() {
+        mNeedsAnimationCancel = true;
+        mInVrAtChromeLaunch = true;
         if (mInVr) return;
 
-        mNeedsAnimationCancel = true;
         mEnterVrOnStartup = true;
 
         // TODO(mthiesse): Assuming we've gone through DON flow saves ~2 seconds on VR entry. See
         // the comments in enterVr(). This may not always be the case in the future, but for now
         // it's a reasonable assumption.
         mDonSucceeded = true;
-        mInVrAtChromeLaunch = true;
 
         if (!mPaused) enterVrAfterDon();
     }
@@ -1362,24 +1362,23 @@ public class VrShellDelegate
             });
         }
 
+        mCancellingEntryAnimation = false;
+
         if (mEnterVrOnStartup) {
             // This means that Chrome was started with a VR intent, so we should enter VR.
             // TODO(crbug.com/776235): VR intents are dispatched to ChromeActivity via a launcher
             // which should handle the DON flow to simplify the logic in VrShellDelegate.
             assert !mProbablyInDon;
             if (DEBUG_LOGS) Log.i(TAG, "onResume: entering VR mode for VR intent");
-            mCancellingEntryAnimation = false;
             if (enterVrInternal() == ENTER_VR_CANCELLED) {
                 cancelPendingVrEntry();
             }
         } else if (mDonSucceeded) {
-            mCancellingEntryAnimation = false;
             handleDonFlowSuccess();
         } else {
             if (mProbablyInDon) {
                 // This means the user backed out of the DON flow, and we won't be entering VR.
                 maybeSetPresentResult(false, mDonSucceeded);
-
                 shutdownVr(true, false);
             }
             // If we were resumed at the wrong density, we need to trigger activity recreation.
@@ -1426,10 +1425,6 @@ public class VrShellDelegate
         // are safe.
         if (mInVr) mVrShell.pause();
         if (mShowingDaydreamDoff || mProbablyInDon) return;
-
-        // TODO(mthiesse): When the user resumes Chrome in a 2D context, we don't want to tear down
-        // VR UI, so for now, exit VR.
-        shutdownVr(true /* disableVrMode */, false /* stayingInChrome */);
     }
 
     protected void onPause() {
@@ -1440,10 +1435,6 @@ public class VrShellDelegate
         unregisterDaydreamIntent(mVrDaydreamApi);
         if (mVrSupportLevel == VrSupportLevel.VR_NOT_AVAILABLE) return;
 
-        // TODO(ymalik): We should be able to remove this if we handle it for multi-window in
-        // {@link onMultiWindowModeChanged} since we're calling it in onStop.
-        if (!mInVr && !mProbablyInDon) cancelPendingVrEntry();
-
         // When the active web page has a vrdisplayactivate event handler,
         // mListeningForWebVrActivate should be set to true, which means a vrdisplayactive event
         // should be fired once DON flow finished. However, DON flow will pause our activity,
@@ -1462,12 +1453,12 @@ public class VrShellDelegate
     private void onStart() {
         mStopped = false;
         if (mDonSucceeded) setWindowModeForVr();
+        if (mInVr && !mVrDaydreamApi.isInVrSession()) shutdownVr(true, false);
     }
 
     private void onStop() {
         if (DEBUG_LOGS) Log.i(TAG, "onStop");
         mStopped = true;
-        if (!mProbablyInDon) cancelPendingVrEntry();
         assert !mCancellingEntryAnimation;
     }
 

chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/mock/MockVrDaydreamApi.java

@@ -100,4 +100,9 @@ public class MockVrDaydreamApi implements VrDaydreamApi {
     public void setForwardSetupIntent(boolean forward) {
         mForwardSetupIntent = forward;
     }
+
+    @Override
+    public boolean isInVrSession() {
+        return true;
+    }
 }