Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/multiwindow/MultiWindowUtils.java

+// Copyright 2015 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.multiwindow;
+
+import android.annotation.TargetApi;
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Build;
+import android.text.TextUtils;
+
+import org.chromium.base.ApplicationStatus;
+import org.chromium.chrome.browser.ChromeMobileApplication;
+import org.chromium.chrome.browser.ChromeTabbedActivity;
+import org.chromium.chrome.browser.document.ChromeLauncherActivity;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * Utilities for detecting multi-window/multi-instance support.
+ *
+ * Thread-safe: This class may be accessed from any thread.
+ */
+public class MultiWindowUtils {
+
+    private static AtomicReference<MultiWindowUtils> sInstance =
+            new AtomicReference<MultiWindowUtils>();
+
+    /**
+     * Returns the singleton instance of MultiWindowUtils, creating it if needed.
+     */
+    public static MultiWindowUtils getInstance() {
+        if (sInstance.get() == null) {
+            ChromeMobileApplication application =
+                    (ChromeMobileApplication) ApplicationStatus.getApplicationContext();
+            sInstance.compareAndSet(null, application.createMultiWindowUtils());
+        }
+        return sInstance.get();
+    }
+
+    /**
+     * @param activity The {@link Activity} to check.
+     * @return Whether or not {@code activity} is currently in multi-window mode.
+     */
+    public boolean isMultiWindow(Activity activity) {
+        // This logic is overridden in a subclass.
+        return false;
+    }
+
+    /**
+     * @param activity The {@link Activity} to check.
+     * @return Whether or not {@code activity} should run in multi-instance mode.
+     */
+    public boolean shouldRunInMultiInstanceMode(ChromeLauncherActivity activity) {
+        return Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP
+                && TextUtils.equals(activity.getIntent().getAction(), Intent.ACTION_MAIN)
+                && isMultiWindow(activity)
+                && activity.isChromeBrowserActivityRunning();
+    }
+
+    /**
+     * Makes |intent| able to support multi-instance in multi-window mode.
+     */
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    public void makeMultiInstanceIntent(Activity activity, Intent intent) {
+        if (activity instanceof ChromeLauncherActivity && isMultiWindow(activity)) {
+            if (TextUtils.equals(ChromeTabbedActivity.class.getName(),
+                    intent.getComponent().getClassName())) {
+                intent.setClassName(activity, MultiInstanceChromeTabbedActivity.class.getName());
+            }
+            intent.setFlags(intent.getFlags()
+                    & ~(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NEW_DOCUMENT));
+        }
+    }
+}