Switch WebVR to handle GvrApi management through VrShellDelegate

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.vr_shell;
 
 import android.app.Activity;
 import android.content.Intent;
 import android.content.pm.ActivityInfo;
 import android.os.StrictMode;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewGroup.LayoutParams;
 import android.view.WindowManager;
 
 import org.chromium.base.Log;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
 import org.chromium.chrome.browser.ChromeTabbedActivity;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 
 /**
  * Manages interactions with the VR Shell.
  */
+@JNINamespace("vr_shell")
 public class VrShellDelegate {
     private static final String TAG = "VrShellDelegate";
 
     private ChromeTabbedActivity mActivity;
 
     private boolean mVrShellEnabled;
 
     private Class<? extends VrShellInterface> mVrShellClass;
     private VrShellInterface mVrShellView;
     private boolean mInVr;
     private int mRestoreSystemUiVisibilityFlag = -1;
     private ViewGroup mParentView;
     private String mVrExtra;
+    private long mNativeVrShellDelegate;
 
     public VrShellDelegate(ChromeTabbedActivity activity, ViewGroup parentView) {
         mActivity = activity;
         mParentView = parentView;
 
         mVrShellClass = maybeFindVrShell();
         if (mVrShellClass != null) {
             mVrShellEnabled = true;
             try {
                 mVrExtra = (String) mVrShellClass.getField("VR_EXTRA").get(null);
             } catch (IllegalAccessException | IllegalArgumentException | NoSuchFieldException e) {
                 Log.e(TAG, "Unable to read VR_EXTRA field", e);
                 mVrShellEnabled = false;
             }
         }
     }
 
+    public void onNativeLibraryReady() {

[Ted C, 2016/09/20 20:31:11]

all public methods should have some sort of documentation

+        mNativeVrShellDelegate = nativeInit();
+    }
+
     @SuppressWarnings("unchecked")
     private Class<? extends VrShellInterface> maybeFindVrShell() {
         try {
             return (Class<? extends VrShellInterface>) Class
                     .forName("org.chromium.chrome.browser.vr_shell.VrShell");
         } catch (ClassNotFoundException e) {
             return null;
         }
     }
 
     /**
      * Enters VR Shell, displaying browser UI and tab contents in VR.
      *
      * This function performs native initialization, and so must only be called after native
      * libraries are ready.
      * @Returns Whether or not we are in VR when this function returns.
      */
     public boolean enterVRIfNecessary() {

[Ted C, 2016/09/20 20:31:11]

could this just take a boolean param isWebVR?  same for exit?

-        if (!mVrShellEnabled) return false;
+        if (!mVrShellEnabled || mNativeVrShellDelegate == 0) return false;
         if (mInVr) return true;
         // VrShell must be initialized in Landscape mode due to a bug in the GVR library.
         mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
         if (!createVrShell()) {
             mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
             return false;
         }
         addVrViews();
         setupVrModeWindowFlags();
-        mVrShellView.onNativeLibraryReady();
+        mVrShellView.onNativeLibraryReady(mNativeVrShellDelegate);
         mVrShellView.setVrModeEnabled(true);
         mInVr = true;
         return true;
     }
 
+    @CalledByNative
+    public boolean enterWebVRIfNecessary() {
+        if (enterVRIfNecessary()) {
+            mVrShellView.setWebVrModeEnabled(true);
+            return true;
+        }
+        return false;
+    }
+
+    @CalledByNative
+    public boolean exitWebVRIfNecessary() {
+        if (!mInVr) return false;
+        mVrShellView.setWebVrModeEnabled(false);
+        // TODO(bajones): Once VR Shell can be invoked outside of WebVR this
+        // should no longer exit the shell outright. Need a way to determine
+        // how VrShell was created.
+        return exitVRIfNecessary();
+    }
+
     /**
      * Resumes VR Shell.
      */
     public void resumeVR() {
         setupVrModeWindowFlags();
         mVrShellView.resume();
     }
 
     /**
      * Pauses VR Shell.
      */
     public void pauseVR() {
         mVrShellView.pause();
     }
 
     /**
      * Exits VR Shell, performing all necessary cleanup.
      * @Returns Whether or not we exited VR.
      */
     public boolean exitVRIfNecessary() {
         if (!mInVr) return false;
+        if (nativeExitVRIfNecessary(mNativeVrShellDelegate)) {
+            // In this scenario we need to wait for WebVR to shut down before
+            // removing the VrShell. exitVRIfNecessary will be called again (by
+            // exitWebVRIfNecessary) when it's safe to destroy the VrShell.

[Ted C, 2016/09/20 20:31:11]

that is an odd semantics.  should we pull out a distinct destroy call and have
it call that instead of a method meaning two things?

+            return true;
+        }
         mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
         mVrShellView.setVrModeEnabled(false);
         mVrShellView.pause();
         removeVrViews();
         clearVrModeWindowFlags();
         destroyVrShell();
         mInVr = false;
         return true;
     }
 
@@ skipping 68 matching lines @@
     public boolean isInVR() {
         return mInVr;
     }
 
     /**
      * @return Whether or not VR Shell is currently enabled.
      */
     public boolean isVrShellEnabled() {
         return mVrShellEnabled;
     }
+
+    private native long nativeInit();
+
+    private native boolean nativeExitVRIfNecessary(long nativeVrShellDelegate);
 }