Make BrowserCdmCast::Initialize() a virtual function so that a subclass can...

Make BrowserCdmCast::Initialize() a virtual function so that a subclass can override the initialization routine.

BUG=internal b/20222899

Review URL: https://codereview.chromium.org/1124073006

Cr-Commit-Position: refs/heads/master@{#330195}

chromecast/media/cdm/browser_cdm_cast.cc

@@ -39,6 +39,8 @@ void BrowserCdmCast::Initialize(
   legacy_session_error_cb_ = legacy_session_error_cb;
   session_keys_change_cb_ = session_keys_change_cb;
   session_expiration_update_cb_ = session_expiration_update_cb;
+
+  InitializeInternal();
 }
 
 int BrowserCdmCast::RegisterPlayer(const base::Closure& new_key_cb,
@@ -198,5 +200,10 @@ void BrowserCdmCastUi::RemoveSession(
   return nullptr;
 }
 
+// A default empty implementation for subclasses that don't need to provide
+// any key system specific initialization.
+void BrowserCdmCast::InitializeInternal() {
+}
+
 }  // namespace media
 }  // namespace chromecast

chromecast/media/cdm/browser_cdm_cast.h

@@ -77,6 +77,10 @@ class BrowserCdmCast : public ::media::BrowserCdm {
  private:
   friend class BrowserCdmCastUi;
 
+  // Allow subclasses to override to provide key sysytem specific
+  // initialization.
+  virtual void InitializeInternal();
+
   ::media::SessionMessageCB session_message_cb_;
   ::media::SessionClosedCB session_closed_cb_;
   ::media::LegacySessionErrorCB legacy_session_error_cb_;