Remove the setting of default accept header for main resources

This CL removes the setting of the default accept header in
FrameFetchContext::addAdditionalRequestHeaders for main resources.
https://chromiumcodereview.appspot.com/313313002/ sets it in
RenderFrameImpl::willSendRequest.

BUG=376025

Review URL: https://codereview.chromium.org/315073005

git-svn-id: svn://svn.chromium.org/blink/trunk@175655 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

@@ -45,8 +45,6 @@
 
 namespace WebCore {
 
-static const char defaultAcceptHeader[] = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
-
 FrameFetchContext::FrameFetchContext(LocalFrame* frame)
     : m_frame(frame)
 {
@@ -91,9 +89,6 @@ void FrameFetchContext::addAdditionalRequestHeaders(Document* document, Resource
 
     m_frame->loader().applyUserAgent(request);
 
-    if (isMainResource)
-        request.setHTTPAccept(defaultAcceptHeader);
-
     // Default to sending an empty Origin header if one hasn't been set yet.
     FrameLoader::addHTTPOriginIfNeeded(request, nullAtom);
 }