Add UMA metrics for multi-window mode and multi-instance

chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java
index 1e6299b37a566da0fea63c3d1d8ac48b218a3850..6fed6bd91ccfc91caaf0730de337d4297a13e4ad 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity2.java
@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser;
 
+import org.chromium.base.metrics.RecordUserAction;
+
 /**
  * A subclass of ChromeTabbedActivity, used in Android N multi-window mode.
  *
@@ -15,4 +17,21 @@ package org.chromium.chrome.browser;
  * named activities makes it possible to bring either existing activity to the foreground on the
  * desired side of the screen when firing an intent.
  */
-public class ChromeTabbedActivity2 extends ChromeTabbedActivity {}
+public class ChromeTabbedActivity2 extends ChromeTabbedActivity {
+    @Override
+    protected void onDeferredStartupForMultiWindowMode() {
+        RecordUserAction.record("Android.MultiWindowMode.MultiInstance.Enter");
+        recordMultiWindowModeScreenWidth();
+    }
+
+    @Override
+    protected void recordMultiWindowModeChangedUserAction(boolean isInMultiWindowMode) {
+        // Record separate user actions for entering/exiting multi-window mode to avoid recording
+        // the same action twice when two instances are running.
+        if (isInMultiWindowMode) {
+            RecordUserAction.record("Android.MultiWindowMode.Enter-SecondInstance");
+        } else {
+            RecordUserAction.record("Android.MultiWindowMode.Exit-SecondInstance");
+        }
+    }
+}