Add a content::GetUserAgent() to wrap webkit_glue::GetUserAgent()

content/common/content_client.h

Index: content/common/content_client.h
diff --git a/content/common/content_client.h b/content/common/content_client.h
index ad07400cf9a2604674e32003c960fc87ce6edc04..154646b6bdc493497bfae7622f3406cd8d5dd96e 100644
--- a/content/common/content_client.h
+++ b/content/common/content_client.h
@@ -44,6 +44,16 @@ class ContentUtilityClient;
 CONTENT_EXPORT void SetContentClient(ContentClient* client);
 CONTENT_EXPORT ContentClient* GetContentClient();
 
+// Returns the user agent string being used by the browser. SetContentClient()
+// must be called prior to calling this, and this routine must be used
+// instead of webkit_glue::GetUserAgent() in order to ensure that we use
+// the same user agent string everywhere.
+// TODO(dpranke): This is caused by webkit_glue being a library that can
+// get linked into multiple linkable objects, causing us to have multiple
+// static values of the user agent. This will be fixed when we clean up
+// webkit_glue.
+CONTENT_EXPORT const std::string& GetUserAgent(const GURL& url);
+
 // Interface that the embedder implements.
 class CONTENT_EXPORT ContentClient {
  public: