media: Send chrome-cache: frfr on first request.

media/blink/resource_multibuffer_data_provider.cc

Index: media/blink/resource_multibuffer_data_provider.cc
diff --git a/media/blink/resource_multibuffer_data_provider.cc b/media/blink/resource_multibuffer_data_provider.cc
index a1e1878bb5cb968ffe677eb1f2d8374f4c45e98d..d0adb08eec544dd36f099ddc4eeb1f48acec946b 100644
--- a/media/blink/resource_multibuffer_data_provider.cc
+++ b/media/blink/resource_multibuffer_data_provider.cc
@@ -85,6 +85,15 @@ void ResourceMultiBufferDataProvider::Start() {
       WebString::FromUTF8(
           net::HttpByteRange::RightUnbounded(byte_pos()).GetHeaderValue()));
 
+  if (url_data_->length() == kPositionNotSpecified &&
+      url_data_->CachedSize() == 0 && url_data_->BytesReadFromCache() == 0) {
+    // This lets flywheel know that we don't have anything previously cached
+    // data for this resource. We can only send it if this is the first request
+    // for this resource.
+    request.SetHTTPHeaderField(WebString::FromUTF8("chrome-proxy"),

[bengr, 2017/04/27 22:10:18]

You are unconditionally adding a header that we conditionally send only to the
data reduction proxy. Doing this will cause VerifyHttpRequestHeaders in
data_reduction_proxy_network_delegate.cc
(https://codesearch.chromium.org/chromium/src/components/data_reduction_proxy/...)
to fail a DCHECK that this header isn't present when the request is not proxied.

Since blink code doesn't know what proxy connection will be used, your best bet
is to add it here as you did and remove it in DRP-specific network code.

The DRP network code calls VerifyHttpRequestHeaders in three places in that
delegate file. Your best bet is to remove 'C-P: frfr' just before those calls if
the d-r-p is not being used. 

[tombergan, 2017/04/27 23:02:52]

Why does the following code not run into the same error?
https://cs.chromium.org/chromium/src/chrome/browser/renderer_context_menu/ren...

[hubbe, 2017/04/27 23:16:26]

Uses different headers..

[hubbe, 2017/04/27 23:21:32]

Or maybe because it dumps two headers into one field?

+                               WebString::FromUTF8("frfr"));
+  }
+
   // We would like to send an if-match header with the request to
   // tell the remote server that we really can't handle files other
   // than the one we already started playing. Unfortunately, doing