Do not show translate bar for MHTML files.

url/url_parse_unittest.cc

Index: url/url_parse_unittest.cc
diff --git a/url/url_parse_unittest.cc b/url/url_parse_unittest.cc
index a65ff858b460149fd5dba2271991c130b78a3a69..7cbccb67e3af01401ac8633716d23b3eed884cbe 100644
--- a/url/url_parse_unittest.cc
+++ b/url/url_parse_unittest.cc
@@ -459,6 +459,34 @@ TEST(URLParser, ExtractFileName) {
   }
 }
 
+TEST(URLParser, ExtractFileExtension) {
+  struct FileCase {
+    const char* input;
+    const char* expected;
+  } file_cases[] = {
+    {"http://www.google.com", NULL},
+    {"http://www.google.com/", NULL},
+    {"http://www.google.com/.foo", NULL},
+    {"http://www.google.com/foo.bar", "bar"},
+    {"http://www.google.com/foo.", ""},
+    {"http://www.google.com/.foo.bar", "bar"},
+    {"http://www.google.com/a.b.c", "c"},
+  };
+
+  for (size_t i = 0; i < ARRAYSIZE(file_cases); i++) {
+    const char* url = file_cases[i].input;
+    int len = static_cast<int>(strlen(url));
+
+    url_parse::Parsed parsed;
+    url_parse::ParseStandardURL(url, len, &parsed);
+
+    url_parse::Component file_name;
+    url_parse::ExtractFileExtension(url, parsed.path, &file_name);
+
+    EXPECT_TRUE(ComponentMatches(url, file_cases[i].expected, file_name));
+  }
+}
+
 // Returns true if the parameter with index |parameter| in the given URL's
 // query string. The expected key can be NULL to indicate no such key index
 // should exist. The parameter number is 1-based.