[Start Surface] Introduce new overview states.

Bug: 982018

Change-Id: Id688ee3656a57e1853715dda09273b3bebc94b0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932476
Commit-Queue: Mia Glaese <glamia@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720354}

chrome/android/chrome_java_sources.gni

@@ -220,6 +220,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/compositor/layouts/LayoutUpdateHost.java",
   "java/src/org/chromium/chrome/browser/compositor/layouts/OverviewModeBehavior.java",
   "java/src/org/chromium/chrome/browser/compositor/layouts/OverviewModeController.java",
+  "java/src/org/chromium/chrome/browser/compositor/layouts/OverviewModeState.java",
   "java/src/org/chromium/chrome/browser/compositor/layouts/SceneChangeObserver.java",
   "java/src/org/chromium/chrome/browser/compositor/layouts/StaticLayout.java",
   "java/src/org/chromium/chrome/browser/compositor/layouts/ToolbarSwipeLayout.java",

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/OverviewModeState.java

+// Copyright 2019 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.compositor.layouts;
+
+import androidx.annotation.IntDef;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * The internal state of the overview mode except show and hide events notified in the {@link
+ * OverviewModeBehavior.OverviewModeObserver}.
+ */
+@IntDef({OverviewModeState.NOT_SHOWN, OverviewModeState.SHOWN_HOMEPAGE,
+        OverviewModeState.SHOWN_TABSWITCHER, OverviewModeState.DISABLED})
+@Retention(RetentionPolicy.SOURCE)
+public @interface OverviewModeState {
+    int NOT_SHOWN = 0;
+    int SHOWN_HOMEPAGE = 1;
+    int SHOWN_TABSWITCHER = 2;
+    int SHOWN_TWO_PANES = 3;
+    int SHOWN_TASKS_ONLY = 4;
+    int DISABLED = 5;
+}