Appending headers of the same name should have their values

joined by ','.
Now, FetchHeaderList::get() is iterating all header list and
append strings to a result joined by ','.

BUG=645497

Review-Url: https://codereview.chromium.org/2587463002
Cr-Commit-Position: refs/heads/master@{#439743}

third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/headers.js

@@ -136,7 +136,7 @@ test(function() {
     headers.append('X-FETCH-TEST-2', 'response test field - append');
     assert_equals(size(headers), 5, 'headers size should increase by 1.');
     assert_equals(headers.get('X-FETCH-Test'),
-                  'response test field - updated',
+                  'response test field - updated,response test field - append',
                   'the value of the first header added should be returned.');
     allValues = headers.getAll('X-FETch-TEST');
     assert_equals(allValues.length, 2);
@@ -156,7 +156,7 @@ test(function() {
     headers = new Headers([['a', 'b'], ['c', 'd'], ['c', 'e']]);
     assert_equals(size(headers), 2, 'headers size should match');
     assert_equals(headers.get('a'), 'b');
-    assert_equals(headers.get('c'), 'd');
+    assert_equals(headers.get('c'), 'd,e');
     assert_equals(headers.getAll('c')[0], 'd');
     assert_equals(headers.getAll('c')[1], 'e');
 
@@ -164,13 +164,25 @@ test(function() {
     var headers2 = new Headers(headers);
     assert_equals(size(headers2), 2, 'headers size should match');
     assert_equals(headers2.get('a'), 'b');
-    assert_equals(headers2.get('c'), 'd');
+    assert_equals(headers2.get('c'), 'd,e');
     assert_equals(headers2.getAll('c')[0], 'd');
     assert_equals(headers2.getAll('c')[1], 'e');
     headers.set('a', 'x');
     assert_equals(headers.get('a'), 'x');
     assert_equals(headers2.get('a'), 'b');
 
+    var headers3 = new Headers();
+    headers3.append('test', 'a');
+    headers3.append('test', '');
+    headers3.append('test', 'b');
+    assert_equals(headers3.get('test'), 'a,,b');
+    headers3.set('test', '');
+    assert_equals(headers3.get('test'), '');
+
+    var headers4 = new Headers();
+    headers4.append('foo', '');
+    headers4.append('foo', 'a');
+    assert_equals(headers4.get('foo'), ',a');
     // new Headers with Dictionary
     headers = new Headers({'a': 'b', 'c': 'd'});
     assert_equals(size(headers), 2, 'headers size should match');

third_party/WebKit/Source/modules/fetch/FetchHeaderList.cpp

@@ -87,13 +87,20 @@ void FetchHeaderList::remove(const String& name) {
 
 bool FetchHeaderList::get(const String& name, String& result) const {
   const String lowercasedName = name.lower();
-  for (size_t i = 0; i < m_headerList.size(); ++i) {
-    if (m_headerList[i]->first == lowercasedName) {
-      result = m_headerList[i]->second;
-      return true;
+  bool found = false;
+  for (const auto& header : m_headerList) {
+    if (header->first == lowercasedName) {
+      if (!found) {
+        result = "";
+        result.append(header->second);
+        found = true;
+      } else {
+        result.append(",");
+        result.append(header->second);
+      }
     }
   }
-  return false;
+  return found;
 }
 
 void FetchHeaderList::getAll(const String& name, Vector<String>& result) const {

third_party/WebKit/Source/modules/fetch/Headers.cpp

@@ -177,8 +177,9 @@ String Headers::get(const String& name, ExceptionState& exceptionState) {
     exceptionState.throwTypeError("Invalid name");
     return String();
   }
-  // "2. Return the value of the first header in header list whose name is
-  //     |name|, and null otherwise."
+  // "2. If there is no header in header list whose name is |name|,
+  //     return null."
+  // "3. Return the combined value given |name| and header list."
   String result;
   m_headerList->get(name, result);
   return result;