Plumb CdmConfig and KeySystem through WebCdmImpl

Meant to do this earlier in:
https://chromium-review.googlesource.com/c/chromium/src/+/1534711

With this final step we can get the pieces we need to pass from WMPI
to the VideoDecodeStatsReporter.

Bug: 907909
Change-Id: Ic0c4055071435b273e80aba9bf4bdde03c139d7d
TBR: sandersd@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539904
Commit-Queue: Chrome Cunningham <chcunningham@chromium.org>
Auto-Submit: Chrome Cunningham <chcunningham@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644785}

media/blink/webcontentdecryptionmodule_impl.cc

@@ -159,4 +159,12 @@ WebContentDecryptionModuleImpl::GetCdmContextRef() {
   return adapter_->GetCdmContextRef();
 }
 
+std::string WebContentDecryptionModuleImpl::GetKeySystem() const {
+  return adapter_->GetKeySystem();
+}
+
+CdmConfig WebContentDecryptionModuleImpl::GetCdmConfig() const {
+  return adapter_->GetCdmConfig();
+}
+
 }  // namespace media

media/blink/webcontentdecryptionmodule_impl.h

@@ -9,10 +9,12 @@
 #include <stdint.h>
 
 #include <memory>
+#include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
+#include "media/base/cdm_config.h"
 #include "media/blink/media_blink_export.h"
 #include "third_party/blink/public/platform/web_content_decryption_module.h"
 #include "third_party/blink/public/platform/web_content_decryption_module_result.h"
@@ -53,6 +55,10 @@ class MEDIA_BLINK_EXPORT WebContentDecryptionModuleImpl
 
   std::unique_ptr<CdmContextRef> GetCdmContextRef();
 
+  std::string GetKeySystem() const;
+
+  CdmConfig GetCdmConfig() const;
+
  private:
   friend CdmSessionAdapter;