Initialize the message center as part of the testing browser process

chrome/browser/usb/web_usb_detector_unittest.cc

 // 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.
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/browser_process.h"
 #include "chrome/browser/usb/web_usb_detector.h"
 #include "device/base/mock_device_client.h"
 #include "device/usb/mock_usb_device.h"
 #include "device/usb/mock_usb_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/notification.h"
 #include "ui/message_center/notification_delegate.h"
 #include "url/gurl.h"
 
@@ skipping 14 matching lines @@
 const char* kLandingPage_3 = "https://www.google.com/C";
 
 }  // namespace
 
 class WebUsbDetectorTest : public testing::Test {
  public:
   WebUsbDetectorTest() {}
   ~WebUsbDetectorTest() override = default;
 
   void SetUp() override {
-    message_center::MessageCenter::Initialize();
-    message_center_ = message_center::MessageCenter::Get();
+    message_center_ = g_browser_process->message_center();
     ASSERT_TRUE(message_center_ != nullptr);
   }
 
-  void TearDown() override { message_center::MessageCenter::Shutdown(); }
+  void TearDown() override { message_center_ = nullptr; }
 
  protected:
   device::MockDeviceClient device_client_;
   message_center::MessageCenter* message_center_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WebUsbDetectorTest);
 };
 
 TEST_F(WebUsbDetectorTest, UsbDeviceAddedAndRemoved) {
@@ skipping 337 matching lines @@
   EXPECT_EQ(expected_message_3, notification_3->message());
   EXPECT_TRUE(notification_3->delegate() != nullptr);
 
   device_client_.usb_service()->RemoveDevice(device_1);
   EXPECT_EQ(nullptr, message_center_->FindVisibleNotificationById(guid_1));
 
   device_client_.usb_service()->RemoveDevice(device_3);
   EXPECT_EQ(nullptr, message_center_->FindVisibleNotificationById(guid_3));
 }
 #endif  // !OS_WIN