Introduce CdmContext interface.

content/renderer/media/crypto/renderer_cdm_manager.cc

Index: content/renderer/media/crypto/renderer_cdm_manager.cc
diff --git a/content/renderer/media/crypto/renderer_cdm_manager.cc b/content/renderer/media/crypto/renderer_cdm_manager.cc
index 3bfdc6e0709f3a474b16b5b5274d506522f8b7ed..b61d7d723c51bf35b67a3cba0ee06a9d7fff2c29 100644
--- a/content/renderer/media/crypto/renderer_cdm_manager.cc
+++ b/content/renderer/media/crypto/renderer_cdm_manager.cc
@@ -7,6 +7,7 @@
 #include "base/stl_util.h"
 #include "content/common/media/cdm_messages.h"
 #include "content/renderer/media/crypto/proxy_media_keys.h"
+#include "media/base/cdm_context.h"
 
 namespace content {
 
@@ -18,7 +19,7 @@ const size_t kMaxSessionMessageLength = 10240;  // 10 KB
 
 RendererCdmManager::RendererCdmManager(RenderFrame* render_frame)
     : RenderFrameObserver(render_frame),
-      next_cdm_id_(media::MediaKeys::kInvalidCdmId + 1) {
+      next_cdm_id_(media::CdmContext::kInvalidCdmId + 1) {
 }
 
 RendererCdmManager::~RendererCdmManager() {
@@ -127,7 +128,7 @@ void RendererCdmManager::OnSessionError(int cdm_id,
 
 int RendererCdmManager::RegisterMediaKeys(ProxyMediaKeys* media_keys) {
   int cdm_id = next_cdm_id_++;
-  DCHECK_NE(cdm_id, media::MediaKeys::kInvalidCdmId);
+  DCHECK_NE(cdm_id, media::CdmContext::kInvalidCdmId);
   DCHECK(!ContainsKey(proxy_media_keys_map_, cdm_id));
   proxy_media_keys_map_[cdm_id] = media_keys;
   return cdm_id;