Catching more errors when parsing ICE server URLs.

Every malformed URL should now produce an error message in JS, rather than
silently failing and possibly printing a warning message to the console (and
possibly crashing).

Also added some unit tests, and made "ParseIceServers" public.

BUG=445002

Review URL: https://codereview.webrtc.org/1344143002

Cr-Commit-Position: refs/heads/master@{#10186}

webrtc/base/stringencode.cc

@@ -556,7 +556,6 @@ std::string s_transform(const std::string& source, Transform t) {
 
 size_t tokenize(const std::string& source, char delimiter,
                 std::vector<std::string>* fields) {
-  RTC_DCHECK(fields);
   fields->clear();
   size_t last = 0;
   for (size_t i = 0; i < source.length(); ++i) {
@@ -573,6 +572,21 @@ size_t tokenize(const std::string& source, char delimiter,
   return fields->size();
 }
 
+size_t tokenize_with_empty_tokens(const std::string& source,
+                                  char delimiter,
+                                  std::vector<std::string>* fields) {
+  fields->clear();
+  size_t last = 0;
+  for (size_t i = 0; i < source.length(); ++i) {
+    if (source[i] == delimiter) {
+      fields->push_back(source.substr(last, i - last));
+      last = i + 1;
+    }
+  }
+  fields->push_back(source.substr(last, source.length() - last));
+  return fields->size();
+}
+
 size_t tokenize_append(const std::string& source, char delimiter,
                        std::vector<std::string>* fields) {
   if (!fields) return 0;

webrtc/base/stringencode.h

@@ -146,6 +146,11 @@ size_t split(const std::string& source, char delimiter,
 size_t tokenize(const std::string& source, char delimiter,
                 std::vector<std::string>* fields);
 
+// Tokenize, including the empty tokens.
+size_t tokenize_with_empty_tokens(const std::string& source,
+                                  char delimiter,
+                                  std::vector<std::string>* fields);
+
 // Tokenize and append the tokens to fields. Return the new size of fields.
 size_t tokenize_append(const std::string& source, char delimiter,
                        std::vector<std::string>* fields);

webrtc/base/stringencode_unittest.cc

@@ -298,6 +298,22 @@ TEST(TokenizeTest, TokenizeWithMarks) {
   ASSERT_STREQ("E F", fields.at(3).c_str());
 }
 
+TEST(TokenizeTest, TokenizeWithEmptyTokens) {
+  std::vector<std::string> fields;
+  EXPECT_EQ(3ul, tokenize_with_empty_tokens("a.b.c", '.', &fields));
+  EXPECT_EQ("a", fields[0]);
+  EXPECT_EQ("b", fields[1]);
+  EXPECT_EQ("c", fields[2]);
+
+  EXPECT_EQ(3ul, tokenize_with_empty_tokens("..c", '.', &fields));
+  EXPECT_TRUE(fields[0].empty());
+  EXPECT_TRUE(fields[1].empty());
+  EXPECT_EQ("c", fields[2]);
+
+  EXPECT_EQ(1ul, tokenize_with_empty_tokens("", '.', &fields));
+  EXPECT_TRUE(fields[0].empty());
+}
+
 TEST(TokenizeFirstTest, NoLeadingSpaces) {
   std::string token;
   std::string rest;
@@ -428,4 +444,5 @@ TEST(BoolTest, RoundTrip) {
   EXPECT_TRUE(FromString(ToString(false), &value));
   EXPECT_FALSE(value);
 }
+
 }  // namespace rtc