ServiceWorker: Fix conversion from Request headers to WebServiceWorkerRequest headers

Source/platform/exported/WebServiceWorkerRequest.cpp

Index: Source/platform/exported/WebServiceWorkerRequest.cpp
diff --git a/Source/platform/exported/WebServiceWorkerRequest.cpp b/Source/platform/exported/WebServiceWorkerRequest.cpp
index 1a390da75d4611b1165cddd3a42ff4f73ed8ad4b..ac31c7ba7a38d74121e1f4ad63f1b8ad67b73207 100644
--- a/Source/platform/exported/WebServiceWorkerRequest.cpp
+++ b/Source/platform/exported/WebServiceWorkerRequest.cpp
@@ -60,9 +60,20 @@ WebString WebServiceWorkerRequest::method() const
 
 void WebServiceWorkerRequest::setHeader(const WebString& key, const WebString& value)
 {
+    ASSERT(String(key) == String(key).lower());

[horo, 2014/09/17 21:13:09]

The header key in content::ServiceWorkerFetchRequest is not lowercased.
So blink::WebServiceWorkerRequest::setHeader() called from
content::ServiceWorkerScriptContext::OnFetchEvent() will crash here.

[jkarlin, 2014/09/18 13:43:43]

Done. Removed lowercase requirement.  HTTPHeaderMap uses a casefolding hash so
lower is unnecessary.  I'll use a casefolding hash equivalent in the browser as
well.

     if (equalIgnoringCase(key, "referer"))
         return;
-    m_private->m_headers.add(key, value);
+    m_private->m_headers.set(key, value);
+}
+
+void WebServiceWorkerRequest::appendHeader(const WebString& key, const WebString& value)
+{
+    ASSERT(String(key) == String(key).lower());
+    if (equalIgnoringCase(key, "referer"))
+        return;
+    HTTPHeaderMap::AddResult result = m_private->m_headers.add(key, value);
+    if (!result.isNewEntry)
+        result.storedValue->value = result.storedValue->value + ", " + String(value);

[jochen (gone - plz use gerrit), 2014/09/17 19:21:28]

would it make sense to add a check that we only do this for headers where this
is valid?

or what happens if the same key/value pair is set multiple times? should we
still append?

[jkarlin, 2014/09/18 13:43:43]

Good question, and I don't have a good answer.  This CL makes Fetch behave like
Blink's WebURLLoaderImpl: 
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
which seems like a good starting place.
They'll be duplicated, which seems reasonable.  This is also the behavior of
WebURLLoader.

 }
 
 void WebServiceWorkerRequest::visitHTTPHeaderFields(WebHTTPHeaderVisitor* headerVisitor) const