Store, use and send etags.

media/blink/resource_multibuffer_data_provider.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/blink/resource_multibuffer_data_provider.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 66 matching lines @@
         FROM_HERE, base::Bind(&ResourceMultiBufferDataProvider::Terminate,
                               weak_factory_.GetWeakPtr()));
     return;
   }
 
   request.setHTTPHeaderField(
       WebString::fromUTF8(net::HttpRequestHeaders::kRange),
       WebString::fromUTF8(
           net::HttpByteRange::RightUnbounded(byte_pos()).GetHeaderValue()));
 
+  if (!url_data_->etag().empty()) {
+    request.setHTTPHeaderField(WebString::fromUTF8("If-Match"),
+                               WebString::fromUTF8(url_data_->etag()));
+  }
+
   url_data_->frame()->setReferrerForRequest(request, blink::WebURL());
 
   // Disable compression, compression for audio/video doesn't make sense...
   request.setHTTPHeaderField(
       WebString::fromUTF8(net::HttpRequestHeaders::kAcceptEncoding),
       WebString::fromUTF8("identity;q=1, *;q=0"));
 
   // Check for our test WebURLLoader.
   std::unique_ptr<WebURLLoader> loader;
   if (test_loader_) {
@@ skipping 137 matching lines @@
     redirects_to_ = GURL();
   }
 
   base::Time last_modified;
   if (base::Time::FromString(
           response.httpHeaderField("Last-Modified").utf8().data(),
           &last_modified)) {
     destination_url_data->set_last_modified(last_modified);
   }
 
+  destination_url_data->set_etag(
+      response.httpHeaderField("ETag").utf8().data());
+
   destination_url_data->set_valid_until(base::Time::Now() +
                                         GetCacheValidUntil(response));
 
   uint32_t reasons = GetReasonsForUncacheability(response);
   destination_url_data->set_cacheable(reasons == 0);
   UMA_HISTOGRAM_BOOLEAN("Media.CacheUseful", reasons == 0);
   int shift = 0;
   int max_enum = base::bits::Log2Ceiling(kMaxReason);
   while (reasons) {
     DCHECK_LT(shift, max_enum);  // Sanity check.
@@ skipping 285 matching lines @@
   }
 
   if (byte_pos() != first_byte_position) {
     return false;
   }
 
   return true;
 }
 
 }  // namespace media