Refactor KeySystems code to call a function to populate the info. (relanding r221932)

content/public/renderer/content_renderer_client.h

Index: content/public/renderer/content_renderer_client.h
diff --git a/content/public/renderer/content_renderer_client.h b/content/public/renderer/content_renderer_client.h
index 24a45101a6d2810d326d165b3af4f169b6a59a11..fcb8e56b276f48e0a985ef49fa40257534e02f00 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -6,6 +6,7 @@
 #define CONTENT_PUBLIC_RENDERER_CONTENT_RENDERER_CLIENT_H_
 
 #include <string>
+#include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string16.h"
@@ -51,6 +52,7 @@ namespace content {
 
 class RenderView;
 class SynchronousCompositor;
+struct KeySystemInfo;
 struct WebPluginInfo;
 
 // Embedder API for participating in renderer logic.
@@ -244,6 +246,10 @@ class CONTENT_EXPORT ContentRendererClient {
   // Returns true if the page at |url| can use Pepper MediaStream APIs.
   virtual bool AllowPepperMediaStreamAPI(const GURL& url);
 
+  // Gives the embedder a chance to register the key system(s) it supports by
+  // populating |key_systems|.
+  virtual void AddKeySystems(std::vector<KeySystemInfo>* key_systems);
+
   // Returns true if we should report a detailed message (including a stack
   // trace) for console [logs|errors|exceptions]. |source| is the WebKit-
   // reported source for the error; this can point to a page or a script,