Use copy-swap idiom for GURL::operator=

url/gurl_unittest.cc

Index: url/gurl_unittest.cc
diff --git a/url/gurl_unittest.cc b/url/gurl_unittest.cc
index ddb55d8902d71725805f3fd9b7cb53187335c81d..c164aed97161792ed20cd96fcd3ee7ed0a82653f 100644
--- a/url/gurl_unittest.cc
+++ b/url/gurl_unittest.cc
@@ -136,6 +136,41 @@ TEST(GURLTest, Copy) {
   EXPECT_EQ("", invalid2.ref());
 }
 
+TEST(GURLTest, Assign) {
+  GURL url(WStringToUTF16(L"http://user:pass@google.com:99/foo;bar?q=a#ref"));
+
+  GURL url2;
+  url2 = url;
+  EXPECT_TRUE(url2.is_valid());
+
+  EXPECT_EQ("http://user:pass@google.com:99/foo;bar?q=a#ref", url2.spec());
+  EXPECT_EQ("http", url2.scheme());
+  EXPECT_EQ("user", url2.username());
+  EXPECT_EQ("pass", url2.password());
+  EXPECT_EQ("google.com", url2.host());
+  EXPECT_EQ("99", url2.port());
+  EXPECT_EQ(99, url2.IntPort());
+  EXPECT_EQ("/foo;bar", url2.path());
+  EXPECT_EQ("q=a", url2.query());
+  EXPECT_EQ("ref", url2.ref());
+
+  // Assignment of invalid URL should be invalid
+  GURL invalid;
+  GURL invalid2;
+  invalid2 = invalid;
+  EXPECT_FALSE(invalid2.is_valid());
+  EXPECT_EQ("", invalid2.spec());
+  EXPECT_EQ("", invalid2.scheme());
+  EXPECT_EQ("", invalid2.username());
+  EXPECT_EQ("", invalid2.password());
+  EXPECT_EQ("", invalid2.host());
+  EXPECT_EQ("", invalid2.port());
+  EXPECT_EQ(url_parse::PORT_UNSPECIFIED, invalid2.IntPort());
+  EXPECT_EQ("", invalid2.path());
+  EXPECT_EQ("", invalid2.query());
+  EXPECT_EQ("", invalid2.ref());
+}
+
 TEST(GURLTest, CopyFileSystem) {
   GURL url(WStringToUTF16(L"filesystem:https://user:pass@google.com:99/t/foo;bar?q=a#ref"));