Implement Chromium side of MediaKeys.isTypeSupported().

content/renderer/media/webcontentdecryptionmodule_impl.cc

Index: content/renderer/media/webcontentdecryptionmodule_impl.cc
diff --git a/content/renderer/media/webcontentdecryptionmodule_impl.cc b/content/renderer/media/webcontentdecryptionmodule_impl.cc
index 9dcb39ee9ca98931c5f49c05035f805ed883e846..6ba5cc0c9e3ab0564368a8c7e8af3f74f2a1477f 100644
--- a/content/renderer/media/webcontentdecryptionmodule_impl.cc
+++ b/content/renderer/media/webcontentdecryptionmodule_impl.cc
@@ -16,6 +16,7 @@
 #include "content/renderer/media/crypto/key_systems.h"
 #include "content/renderer/media/webcontentdecryptionmodulesession_impl.h"
 #include "media/base/media_keys.h"
+#include "net/base/mime_util.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/web/WebSecurityOrigin.h"
 #include "url/gurl.h"
@@ -76,6 +77,108 @@ WebContentDecryptionModuleImpl* WebContentDecryptionModuleImpl::Create(
   return new WebContentDecryptionModuleImpl(adapter);
 }
 
+// static
+blink::WebContentDecryptionModule::KeySystemSupportedResult
+WebContentDecryptionModuleImpl::IsKeySystemSupported(
+    const blink::WebString& key_system,
+    const blink::WebString& init_data_type,
+    const blink::WebString& container,
+    const blink::WebString& codecs,
+    const blink::WebString& capability) {
+  // Continuation (from Blink) of MediaKeys.isTypeSupported() algorithm.
+
+  // 1. If keySystem is an empty string or contains an unrecognized or
+  //    unsupported Key System, return the empty string and abort these steps.
+  //    String comparison is case-sensitive.
+  // 2. If the keySystem implementation is not available and usable, return the
+  //    empty string and abort these steps.
+  // (Emptiness check is in Blink.)
+  // TODO(sandersd): Implement ASCII checks on Blink side.
+  const std::string key_system_ascii = key_system.utf8();
+  if (!IsSupportedKeySystem(key_system_ascii))
+    return blink::WebContentDecryptionModule::NotSupported;
+
+  // 3. Follow the steps for the first matching condition from the following
+  //    list:
+  //    - If keySystem is a value that may be successfully passed to create()
+  //        Let probably result be "probably"
+  //    - Otherwise (as may be the case for strings that are only used for
+  //      discovery)
+  //        Let probably result be "maybe".
+  blink::WebContentDecryptionModule::KeySystemSupportedResult probably_result =
+      (IsConcreteSupportedKeySystem(key_system_ascii) ?

[ddorwin, 2014/09/23 22:48:18]

nit: () is not strictly necessary.

[sandersd (OOO until July 31), 2014/09/24 22:22:34]

Done.

+       blink::WebContentDecryptionModule::ProbablySupported :

[ddorwin, 2014/09/23 22:48:17]

nit: I'm not sure what the style guide says or formatter does, but I'd find this
easier to read if these two lines were indented 4 spaces. WDYT?

[sandersd (OOO until July 31), 2014/09/24 22:22:34]

Done.

+       blink::WebContentDecryptionModule::MaybeSupported);
+
+  // 4. If initDataType was not provided, follow the steps for the first
+  //    matching condition from the following list and abort these steps:
+  //    - If the user agent is not confident that the keySystem implementation
+  //      is available and usable
+  //        Return "maybe"
+  //    - Otherwise
+  //        Return probably result.
+  if (init_data_type.isEmpty())
+    return probably_result;
+
+  // 5. If initDataType is an empty string or contains an unrecognized or
+  //    unsupported initialization data type, return the empty string and abort
+  //    these steps. String comparison is case-sensitive.
+  // 6. If initDataType is not an initialization data type supported by the
+  //    keySystem implementation, return the empty string and abort these steps.
+  // 7. If the keySystem implementation supporting initDataType is not available
+  //    and usable, return the empty string and abort these steps.
+  // (Emptiness check is in Blink.)
+  const std::string init_data_type_ascii = init_data_type.utf8();
+  if (!IsSupportedKeySystemWithInitDataType(key_system_ascii,
+                                            init_data_type_ascii))
+    return blink::WebContentDecryptionModule::NotSupported;
+
+  // 8. If contentType was not provided, follow the steps for the first matching
+  //    condition from the following list and abort these steps:
+  //    - If the user agent is not confident that the keySystem implementation
+  //      supporting initDataType is available and usable
+  //        Return "maybe"
+  //    - Otherwise
+  //        Return probably result.
+  if (container.isEmpty())
+    return probably_result;
+
+  // 9.  If contentType is an empty string or contains an invalid or
+  //     unrecognized MIME type, return the empty string and abort these steps.
+  // 10. Let container be the container type specified by contentType.
+  // 11. Let parameters be the RFC 6381 parameters, if any, specified by
+  //     contentType.
+  // 12. Let media types be the set of media types specified by parameters. It
+  //     may be empty. The case-sensitivity of string comparisons is determined
+  //     by the appropriate RFC or other specification.
+  // 13. If the user agent does not support container, return the empty string
+  //     and abort these steps. The case-sensitivity of string comparisons is
+  //     determined by the appropriate RFC.
+  // 14. If the user agent and keySystem implementation do not support playback
+  //     of encrypted media data for all media types, return the empty string
+  //     and abort these steps.
+  // (Emptiness check is in Blink.)
+  const std::string container_ascii = container.utf8();
+  if (!IsSaneInitDataTypeWithContainer(init_data_type_ascii, container_ascii))
+    return blink::WebContentDecryptionModule::NotSupported;
+
+  bool strip_codec_suffixes = !net::IsStrictMediaMimeType(container_ascii);

[ddorwin, 2014/09/23 22:48:17]

http://crbug.com/374751 also affects this line, so I think we should have an
explicit note.

[sandersd (OOO until July 31), 2014/09/24 22:22:34]

Done.

+  std::vector<std::string> codec_vector;
+  net::ParseCodecString(codecs.utf8(), &codec_vector, strip_codec_suffixes);
+  if (!IsSupportedKeySystemWithMediaMimeType(
+      container_ascii, codec_vector, key_system_ascii))
+    return blink::WebContentDecryptionModule::NotSupported;
+
+  // 15-18. (Capabilities.)
+  // TODO(sandersd): Support capabilities.
+  if (!capability.isEmpty())
+    return blink::WebContentDecryptionModule::NotSupported;
+
+  // TODO(sandersd): If the codecs are all unambiguous and supported, return
+  // |probably_result|. http://crbug.com/374751
+  return blink::WebContentDecryptionModule::MaybeSupported;
+}
+
 WebContentDecryptionModuleImpl::WebContentDecryptionModuleImpl(
     scoped_refptr<CdmSessionAdapter> adapter)
     : adapter_(adapter) {}