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

chrome/browser/webshare/share_service_impl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_WEBSHARE_SHARE_SERVICE_IMPL_H_
 #define CHROME_BROWSER_WEBSHARE_SHARE_SERVICE_IMPL_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/strings/string16.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "third_party/WebKit/public/platform/modules/webshare/webshare.mojom.h"
 
 class GURL;
 
-enum class SharePickerResult {
-  CANCEL,
-  SHARE
-};
-
 // Desktop implementation of the ShareService Mojo service.
 class ShareServiceImpl : public blink::mojom::ShareService {
  public:
   ShareServiceImpl() = default;
   ~ShareServiceImpl() override = default;
 
   static void Create(mojo::InterfaceRequest<ShareService> request);
 
   // blink::mojom::ShareService overrides:
   void Share(const std::string& title,
              const std::string& text,
              const GURL& share_url,
              const ShareCallback& callback) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ShareServiceImplUnittest, ReplacePlaceholders);
 
   // Shows the share picker dialog with |targets| as the list of applications
-  // presented to the user. Passes the result to |callback|. Virtual for
-  // testing.
+  // presented to the user. Passes the result to |callback|. If the user picks a
+  // target, the result passed to |callback| is the manifest URL of the chosen
+  // target, and is null if the user cancelled the share. Virtual for testing.

[Matt Giuca, 2017/02/01 07:04:33]

s/and/or :)

[constantina, 2017/02/01 23:24:21]

Done :)

   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.
   virtual void OpenTargetURL(const GURL& target_url);
 
   // Writes to |url_template_filled|, a copy of |url_template| with all
   // instances of "{title}", "{text}", and "{url}" replaced with
   // |title|, |text|, and |url| respectively.
   // Replaces instances of "{X}" where "X" is any string besides "title",
   // "text", and "url", with an empty string, for forwards compatibility.
   // Returns false, if there are badly nested placeholders.
   // This includes any case in which two "{" occur before a "}", or a "}"
   // occurs with no preceding "{".
   static bool ReplacePlaceholders(base::StringPiece url_template,
                                   base::StringPiece title,
                                   base::StringPiece text,
                                   const GURL& share_url,
                                   std::string* url_template_filled);
 
   void OnPickerClosed(const std::string& title,
                       const std::string& text,
                       const GURL& share_url,
                       const ShareCallback& callback,
-                      SharePickerResult result);
+                      base::Optional<base::string16> result);
 
   DISALLOW_COPY_AND_ASSIGN(ShareServiceImpl);
 };
 
 #endif  // CHROME_BROWSER_WEBSHARE_SHARE_SERVICE_IMPL_H_