Add PlayerTracker and BrowserCdm interfaces.

media/base/browser_cdm.cc

Index: media/base/browser_cdm.cc
diff --git a/tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.cpp b/media/base/browser_cdm.cc
similarity index 56%
copy from tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.cpp
copy to media/base/browser_cdm.cc
index 6b16e41089baf2aceab15833edd91b1eeaa26dfd..2c44e1652ad09cf59125a471c051a86609347325 100644
--- a/tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.cpp
+++ b/media/base/browser_cdm.cc
@@ -2,13 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "part_object_to_gc_derived_class.h"
+#include "media/base/browser_cdm.h"
 
-namespace WebCore {
+namespace media {
 
-void B::trace(Visitor* visitor)
-{
-    visitor->trace(m_a);
+BrowserCdm::BrowserCdm() {
 }
 
+BrowserCdm::~BrowserCdm() {
 }
+
+}  // namespace media