Add std::string StartsWith*/EndsWith* overloads.

We should have done this from the beginning. Thanks to Windows, we're not
going to be able to switch libbase over to std::string_view any time soon.

Bug: N/A
Test: ran tests
Change-Id: Iff2f56986e39de53f3ac484415378af17dacf26b
diff --git a/strings_test.cpp b/strings_test.cpp
index 121197c..b8639ea 100644
--- a/strings_test.cpp
+++ b/strings_test.cpp
@@ -253,6 +253,26 @@
   ASSERT_FALSE(android::base::EndsWithIgnoreCase("foobar", "FOO"));
 }
 
+TEST(strings, StartsWith_std_string) {
+  ASSERT_TRUE(android::base::StartsWith("hello", std::string{"hell"}));
+  ASSERT_FALSE(android::base::StartsWith("goodbye", std::string{"hell"}));
+}
+
+TEST(strings, StartsWithIgnoreCase_std_string) {
+  ASSERT_TRUE(android::base::StartsWithIgnoreCase("HeLlO", std::string{"hell"}));
+  ASSERT_FALSE(android::base::StartsWithIgnoreCase("GoOdByE", std::string{"hell"}));
+}
+
+TEST(strings, EndsWith_std_string) {
+  ASSERT_TRUE(android::base::EndsWith("hello", std::string{"lo"}));
+  ASSERT_FALSE(android::base::EndsWith("goodbye", std::string{"lo"}));
+}
+
+TEST(strings, EndsWithIgnoreCase_std_string) {
+  ASSERT_TRUE(android::base::EndsWithIgnoreCase("HeLlO", std::string{"lo"}));
+  ASSERT_FALSE(android::base::EndsWithIgnoreCase("GoOdByE", std::string{"lo"}));
+}
+
 TEST(strings, EqualsIgnoreCase) {
   ASSERT_TRUE(android::base::EqualsIgnoreCase("foo", "FOO"));
   ASSERT_TRUE(android::base::EqualsIgnoreCase("FOO", "foo"));