Check that containers are supported by Chrome in requestMediaKeySystemAccess().

media/blink/webencryptedmediaclient_impl.cc

 // Copyright 2014 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 "webencryptedmediaclient_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 128 matching lines @@
   // Check that |container_mime_type| and |codecs| are supported by the CDM.
   // This check does not handle extended codecs, so extended codec information
   // is stripped.
   std::vector<std::string> codec_vector;
   net::ParseCodecString(codecs, &codec_vector, true);
   if (!key_systems.IsSupportedCodecCombination(
            key_system, media_type, container_lower, codec_vector)) {
     return false;
   }
 
-  if (codec_vector.empty())
-    return true;
+  // Check that |container_mime_type| is supported by Chrome.
+  if (!net::IsSupportedMediaMimeType(container_lower))

[ddorwin, 2015/03/26 17:55:10]

This would allow, for example, "video/ogg", which is not supported encrypted.
Why doesn't IsSupportedCodecCombination() check the container when codec_vector
is empty?

[sandersd (OOO until July 31), 2015/03/26 18:11:05]

IsSupportedCodecCombination() already makes sure that the CDM supports the
container, so nothing exotic should show up here.

IsSupportedStrictMediaMimeType() returns Maybe when the container requires a
codec list and none is given (but also in other cases we don't support).

+    return false;
 
   // Check that |codecs| are supported by Chrome. This is done primarily to
   // validate extended codecs, but it also ensures that the CDM cannot support
   // codecs that Chrome does not (which could complicate the robustness
   // algorithm).
+  if (codec_vector.empty())
+    return true;
   codec_vector.clear();
   net::ParseCodecString(codecs, &codec_vector, false);
   return (net::IsSupportedStrictMediaMimeType(container_lower, codec_vector) ==
           net::IsSupported);
 }
 
 static bool GetSupportedCapabilities(
     const KeySystems& key_systems,
     const std::string& key_system,
     EmeMediaType media_type,
@@ skipping 526 matching lines @@
     return reporter;
 
   // Reporter not found, so create one.
   auto result =
       reporters_.add(uma_name, make_scoped_ptr(new Reporter(uma_name)));
   DCHECK(result.second);
   return result.first->second;
 }
 
 }  // namespace media