Add help link when Bluetooth adapter is off for WebBluetooth chooser

chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa_controller_unittest.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/extensions/chooser_dialog_cocoa_controller.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include <memory>
 #include <vector>
@@ skipping 724 matching lines @@
       content::BluetoothChooser::AdapterPresence::POWERED_OFF);
   EXPECT_FALSE(table_view_.hidden);
   // Since "Bluetooth turned off." needs to be displayed on the |table_view_|,
   // the number of rows is 1.
   EXPECT_EQ(1, table_view_.numberOfRows);
   // |table_view_| should be disabled since there is no option shown.
   EXPECT_FALSE(table_view_.enabled);
   // No option selected.
   EXPECT_EQ(-1, table_view_.selectedRow);
   ExpectNoRowImage(0);
-  ExpectRowTextIs(
-      0, l10n_util::GetNSString(IDS_BLUETOOTH_DEVICE_CHOOSER_ADAPTER_OFF));
+  // TODO(juncai): test the row text is "Turn on Bluetooth to allow pairing"
+  // after the Mac implementation is done.
+  // https://crbug.com/644168
   EXPECT_FALSE(IsRowPaired(0));
   EXPECT_TRUE(spinner_.hidden);
   EXPECT_TRUE(status_.hidden);
   EXPECT_TRUE(rescan_button_.hidden);
   // Since the adapter is turned off, the previously selected option
   // becomes invalid, the OK button is disabled.
   EXPECT_EQ(0u, mock_chooser_controller_->NumOptions());
   EXPECT_FALSE(connect_button_.enabled);
   EXPECT_TRUE(cancel_button_.enabled);
 
@@ skipping 151 matching lines @@
       MockChooserController::ConnectedPairedStatus::NONE);
 
   // Select option 0 and press "Get help" button.
   [table_view_ selectRowIndexes:[NSIndexSet indexSetWithIndex:0]
            byExtendingSelection:NO];
   EXPECT_CALL(*mock_chooser_controller_, Select(testing::_)).Times(0);
   EXPECT_CALL(*mock_chooser_controller_, Cancel()).Times(0);
   EXPECT_CALL(*mock_chooser_controller_, OpenHelpCenterUrl()).Times(1);
   [help_button_ performClick:chooser_dialog_controller_];
 }