Add an IPC to return the platform supported key-system names in Android.

components/cdm/renderer/android_key_systems.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 "components/cdm/renderer/android_key_systems.h"
+
+#include <string>
+#include <vector>
+
+#include "base/logging.h"
+#include "components/cdm/common/cdm_messages_android.h"
+#include "components/cdm/renderer/widevine_key_systems.h"
+#include "content/public/renderer/render_thread.h"
+
+#include "widevine_cdm_version.h"  // In SHARED_INTERMEDIATE_DIR.
+
+using content::KeySystemInfo;
+using content::SupportedCodecs;
+
+namespace cdm {
+
+static SupportedKeySystemResponse GetSupportedKeySystem(

[ddorwin, 2014/06/10 18:48:04]

ditto on naming

[ycheo (away), 2014/06/11 00:08:22]

Done.

+    const std::string& key_system) {
+  SupportedKeySystemRequest request;
+  SupportedKeySystemResponse response;
+
+  request.key_system = key_system;
+  request.codecs = content::EME_CODEC_WEBM_ALL | content::EME_CODEC_MP4_ALL;
+  content::RenderThread::Get()->Send(
+      new CdmHostMsg_GetSupportedKeySystem(request, &response));
+  DCHECK(response.compositing_codecs & content::EME_CODEC_ALL)

[ddorwin, 2014/06/10 18:48:04]

This only checks that there is at least one supported codec but not that there
aren't additional unsupported codecs. For that, you'd need (!(codecs & ~ALL)) or
(codecs & ALL == codecs).

[ycheo (away), 2014/06/11 00:08:22]

Good catch!.

+      << "unrecognized codec";
+  DCHECK(response.non_compositing_codecs & content::EME_CODEC_ALL)
+      << "unrecognized codec";
+  return response;
+}
+
+void AddAndroidWidevine(std::vector<KeySystemInfo>* concrete_key_systems) {
+  SupportedKeySystemResponse response;
+  response = GetSupportedKeySystem(kWidevineKeySystem);

[ddorwin, 2014/06/10 18:48:04]

merge with the line above.

[ycheo (away), 2014/06/11 00:08:22]

Done.

+  if (response.compositing_codecs != content::EME_CODEC_NONE) {
+    AddWidevineWithCodecs(
+        WIDEVINE,
+        static_cast<SupportedCodecs>(response.compositing_codecs),
+        concrete_key_systems);
+  }
+
+  if (response.non_compositing_codecs != content::EME_CODEC_NONE) {
+    AddWidevineWithCodecs(
+        WIDEVINE_HR_NON_COMPOSITING,
+        static_cast<SupportedCodecs>(response.non_compositing_codecs),
+        concrete_key_systems);
+  }
+}
+
+void AddOtherAndroidSupportedKeySystems(
+    std::vector<KeySystemInfo>* concrete_key_systems) {
+  std::vector<std::string> key_system_names;
+  content::RenderThread::Get()->Send(
+      new CdmHostMsg_GetAllSupportedKeySystemNames(&key_system_names));
+
+  for (std::vector<std::string>::const_iterator it = key_system_names.begin();
+       it != key_system_names.end(); ++it) {
+    if (it->compare(kWidevineKeySystem) == 0)  // Skip Widevine.
+      continue;
+
+    SupportedKeySystemResponse response = GetSupportedKeySystem(*it);
+    if (response.compositing_codecs != content::EME_CODEC_NONE) {

[ddorwin, 2014/06/10 18:48:04]

Don't you want to support non-compositing?

[ycheo (away), 2014/06/11 00:08:22]

no, but the keysyste name suffix '.noncompositing' is only for WV, right?

Do you think I should merge two results compositing_codecs with
non_compositing_codecs?

[ddorwin, 2014/06/11 01:54:01]

Right.

I don't know what the use case is or even if MediaDrmBridge knows. The
non-compositing ones are problematic for normal web pages. Actually, without
support, MediaDrmBridge might dump them all in the compositing list.

This is fine for now, but we may want to discuss.

+      KeySystemInfo info(*it);
+      info.supported_codecs = response.compositing_codecs;
+      concrete_key_systems->push_back(info);
+    }
+  }
+}
+
+}  // namespace cdm