Use base::StartWith() in more places when appropriate.

ui/message_center/views/notification_view_unittest.cc

Index: ui/message_center/views/notification_view_unittest.cc
diff --git a/ui/message_center/views/notification_view_unittest.cc b/ui/message_center/views/notification_view_unittest.cc
index fd236177566a897209f85a129827b8e6f3f07db8..cbf4bac709f7424670def1514faf9f70bb8a212e 100644
--- a/ui/message_center/views/notification_view_unittest.cc
+++ b/ui/message_center/views/notification_view_unittest.cc
@@ -7,6 +7,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ -641,10 +642,12 @@ TEST_F(NotificationViewTest, FormatContextMessageTest) {
   // The url has been elided (it starts with an ellipsis)
   // The end of the domainsuffix is shown
   // the url piece is not shown
-  EXPECT_TRUE(base::UTF16ToUTF8(result).find(
-                  ".veryveryveyrylong.chromium.org") != std::string::npos);
-  EXPECT_TRUE(base::UTF16ToUTF8(result).find("\xE2\x80\xA6") == 0);
-  EXPECT_TRUE(base::UTF16ToUTF8(result).find("hello") == std::string::npos);
+  std::string result_utf8 = base::UTF16ToUTF8(result);
+  EXPECT_TRUE(result_utf8.find(".veryveryveyrylong.chromium.org") !=
+              std::string::npos);
+  EXPECT_TRUE(base::StartsWith(result_utf8, "\xE2\x80\xA6",
+                               base::CompareCase::SENSITIVE));
+  EXPECT_TRUE(result_utf8.find("hello") == std::string::npos);
 }
 
 TEST_F(NotificationViewTest, SlideOut) {