media: Add External Clear Key content browser test on Android

content/shell/renderer/shell_content_renderer_client.h

Index: content/shell/renderer/shell_content_renderer_client.h
diff --git a/content/shell/renderer/shell_content_renderer_client.h b/content/shell/renderer/shell_content_renderer_client.h
index f0e03318f8d60bb9bfd4f92ba70034fe431a0483..7ad69716f5ad688adfb7efb0e91619ebd5f5fd82 100644
--- a/content/shell/renderer/shell_content_renderer_client.h
+++ b/content/shell/renderer/shell_content_renderer_client.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/compiler_specific.h"
+#include "build/build_config.h"
 #include "content/public/renderer/content_renderer_client.h"
 
 namespace web_cache {
@@ -36,6 +37,12 @@ class ShellContentRendererClient : public ContentRendererClient {
   void ExposeInterfacesToBrowser(
       shell::InterfaceRegistry* interface_registry) override;
 
+#if defined(OS_ANDROID)
+  void AddSupportedKeySystems(
+      std::vector<std::unique_ptr<media::KeySystemProperties>>* key_systems)
+      override;
+#endif
+
  private:
   std::unique_ptr<web_cache::WebCacheImpl> web_cache_impl_;
 };