Picker takes a vector of pairs, and passes back the user chosen target.

chrome/browser/webshare/share_service_impl.h

Index: chrome/browser/webshare/share_service_impl.h
diff --git a/chrome/browser/webshare/share_service_impl.h b/chrome/browser/webshare/share_service_impl.h
index bcc2a5575544da2e6dd01c0c0d4a2a1b935206f1..567e081b6a2de47221fc3808ca7d9f54bcd397dd 100644
--- a/chrome/browser/webshare/share_service_impl.h
+++ b/chrome/browser/webshare/share_service_impl.h
@@ -14,11 +14,6 @@
 
 class GURL;
 
-enum class SharePickerResult {
-  CANCEL,
-  SHARE
-};
-
 // Desktop implementation of the ShareService Mojo service.
 class ShareServiceImpl : public blink::mojom::ShareService {
  public:
@@ -41,7 +36,7 @@ class ShareServiceImpl : public blink::mojom::ShareService {
   // testing.
   virtual void ShowPickerDialog(
       const std::vector<base::string16>& targets,
-      const base::Callback<void(SharePickerResult)>& callback);
+      const base::Callback<void(base::Optional<base::string16>)>& callback);
 
   // Opens a new tab and navigates to |target_url|.
   // Virtual for testing purposes.
@@ -65,7 +60,7 @@ class ShareServiceImpl : public blink::mojom::ShareService {
                       const std::string& text,
                       const GURL& share_url,
                       const ShareCallback& callback,
-                      SharePickerResult result);
+                      base::Optional<base::string16> result);
 
   DISALLOW_COPY_AND_ASSIGN(ShareServiceImpl);
 };