Add metrics for triggering of JS dialogs on Android.

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

 // Copyright 2014 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.tab;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.app.Application;
 import android.content.Context;
 import android.content.Intent;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.Rect;
 import android.net.Uri;
 import android.os.Bundle;
 import android.provider.Browser;
 import android.support.annotation.Nullable;
+import android.support.v4.view.ViewCompat;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.ContextThemeWrapper;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
 import android.widget.FrameLayout;
 import android.widget.FrameLayout.LayoutParams;
 
@@ skipping 2100 matching lines @@
     }
 
     /**
      * @return Whether or not the tab is hidden.
      */
     public boolean isHidden() {
         return mIsHidden;
     }
 
     /**
+     * @return Whether the tab can currently be interacted with by the user.  This requires the
+     *         view owned by the Tab to be visible and in a state where the user can interact with
+     *         it (i.e. not in something like the phone tab switcher).
+     */
+    @CalledByNative
+    public boolean isUserInteractable() {
+        return !mIsHidden && ViewCompat.isAttachedToWindow(getView());
+    }
+
+    /**
      * @return Whether or not the tab is in the closing process.
      */
     public boolean isClosing() {
         return mIsClosing;
     }
 
     /**
      * @param closing Whether or not the tab is in the closing process.
      */
     public void setClosing(boolean closing) {
@@ skipping 940 matching lines @@
     private native void nativeLoadOriginalImage(long nativeTabAndroid);
     private native long nativeGetBookmarkId(long nativeTabAndroid, boolean onlyEditable);
     private native boolean nativeIsOfflinePage(long nativeTabAndroid);
     private native OfflinePageItem nativeGetOfflinePage(long nativeTabAndroid);
     private native void nativeSetInterceptNavigationDelegate(long nativeTabAndroid,
             InterceptNavigationDelegate delegate);
     private native void nativeAttachToTabContentManager(long nativeTabAndroid,
             TabContentManager tabContentManager);
     private native boolean nativeHasPrerenderedUrl(long nativeTabAndroid, String url);
 }