media: Stop sending if-match headers for media fetch requests.

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 9ef0684479330e51c6a5fcec9fda27f445c09604..f1f80f07823f60f9f15875d87437c18f44b13d8c 100644
--- a/media/blink/resource_multibuffer_data_provider.cc
+++ b/media/blink/resource_multibuffer_data_provider.cc
@@ -85,10 +85,11 @@ void ResourceMultiBufferDataProvider::Start() {
       WebString::fromUTF8(
           net::HttpByteRange::RightUnbounded(byte_pos()).GetHeaderValue()));
 
-  if (!url_data_->etag().empty()) {
-    request.setHTTPHeaderField(WebString::fromUTF8("If-Match"),
-                               WebString::fromUTF8(url_data_->etag()));
-  }
+  // 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
+  // so will disable the http cache, and possibly other proxies
+  // along the way. See crbug/504194 and crbug/689989 for more information.
 
   url_data_->frame()->setReferrerForRequest(request, blink::WebURL());