[Dial] Refactor DialRegistry and DeviceDescriptionFetcher so they can be used by MediaSinkService

chrome/browser/extensions/api/dial/device_description_fetcher.h

Index: chrome/browser/extensions/api/dial/device_description_fetcher.h
diff --git a/chrome/browser/extensions/api/dial/device_description_fetcher.h b/chrome/browser/extensions/api/dial/device_description_fetcher.h
index 309dc88a60007e340790bdd540412560125c73d2..8a4a8f56745ccfc678df52a224f929a38617a246 100644
--- a/chrome/browser/extensions/api/dial/device_description_fetcher.h
+++ b/chrome/browser/extensions/api/dial/device_description_fetcher.h
@@ -9,13 +9,14 @@
 #include <string>
 
 #include "base/callback.h"
+#include "base/threading/thread_checker.h"
+#include "content/public/browser/browser_thread.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "url/gurl.h"
 
-class Profile;
-
 namespace net {
 class URLFetcher;
+class URLRequestContextGetter;
 }
 
 namespace extensions {
@@ -27,17 +28,18 @@ struct DialDeviceDescriptionData;
 // Used to make a single HTTP GET request with |device_description_url| to fetch
 // a uPnP device description from a DIAL device.  If successful, |success_cb| is
 // invoked with the result; otherwise, |error_cb| is invoked with an error
-// reason.  This class is not thread safe and must be used on the UI thread.
+// reason.
+// This class is not thread safe.
 class DeviceDescriptionFetcher : public net::URLFetcherDelegate {
  public:
   // Used to identify the net::URLFetcher instance for tests.
   static constexpr int kURLFetcherIDForTest = 1;
 
-  // |profile| is unowned; the caller must ensure that this object does not
-  // outlive it.
+  // |request_context| is unowned; the caller must ensure that this object does
+  // not outlive it.
   DeviceDescriptionFetcher(
       const GURL& device_description_url,
-      Profile* profile,
+      net::URLRequestContextGetter* request_context,
       base::OnceCallback<void(const DialDeviceDescriptionData&)> success_cb,
       base::OnceCallback<void(const std::string&)> error_cb);
 
@@ -60,7 +62,9 @@ class DeviceDescriptionFetcher : public net::URLFetcherDelegate {
   void ReportError(const std::string& message);
 
   const GURL device_description_url_;
-  Profile* const profile_;
+  const scoped_refptr<net::URLRequestContextGetter> request_context_;
+  base::ThreadChecker thread_checker_;
+
   base::OnceCallback<void(const DialDeviceDescriptionData&)> success_cb_;
   base::OnceCallback<void(const std::string&)> error_cb_;
   std::unique_ptr<net::URLFetcher> fetcher_;