[chrome.dial] Adds chrome.dial.fetchDeviceDecription API.

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

Index: chrome/browser/extensions/api/dial/dial_registry.h
diff --git a/chrome/browser/extensions/api/dial/dial_registry.h b/chrome/browser/extensions/api/dial/dial_registry.h
index 784aa78aaad577c3e5a8c5ef048b63ed0a389de3..1616dac709e4d78346a4e9340db1cdbeb9a930b0 100644
--- a/chrome/browser/extensions/api/dial/dial_registry.h
+++ b/chrome/browser/extensions/api/dial/dial_registry.h
@@ -72,6 +72,15 @@ class DialRegistry : public DialService::Observer,
   // already active.
   bool DiscoverNow();
 
+  // Returns the URL of the device description for the device identified by
+  // |label|, or an empty GURL if no such device exists.
+  GURL GetDeviceDescriptionURL(const std::string& label) const;
+
+  // Adds a device directly to the registry as if it was discovered.  For tests
+  // only.  Note that if discovery is actually started, this device will be
+  // removed by PruneExpiredDevices().
+  void AddDeviceForTest(const DialDeviceData& device_data);
+
  protected:
   // Returns a new instance of the DIAL service.  Overridden by tests.
   virtual std::unique_ptr<DialService> CreateDialService();