Make update over cellular an option for user

chrome/browser/ui/webui/help/version_updater.h

Index: chrome/browser/ui/webui/help/version_updater.h
diff --git a/chrome/browser/ui/webui/help/version_updater.h b/chrome/browser/ui/webui/help/version_updater.h
index f12e367bcc588bba3ccb8d8ce362ebc7de11b7f8..4111b3389b5c32e62d69a0be4664e5d7d3696806 100644
--- a/chrome/browser/ui/webui/help/version_updater.h
+++ b/chrome/browser/ui/webui/help/version_updater.h
@@ -25,6 +25,7 @@ class VersionUpdater {
   // Update process state machine.
   enum Status {
     CHECKING,
+    NEED_PERMISSION_TO_UPDATE,
     UPDATING,
     NEARLY_UPDATED,
     UPDATED,
@@ -53,8 +54,16 @@ class VersionUpdater {
 
   // Used to update the client of status changes. int parameter is the progress
   // and should only be non-zero for the UPDATING state.
+  // std::string parameter is the version of the available update and should be
+  // empty string when update is not available.
+  // int64_t parameter is the size in bytes of the available update and should
+  // be 0 when update is not available.
   // base::string16 parameter is a message explaining a failure.
-  typedef base::Callback<void(Status, int, const base::string16&)>
+  typedef base::Callback<void(Status,
+                              int,
+                              const std::string&,
+                              const int64_t,
+                              const base::string16&)>

[xiyuan, 2017/05/11 20:37:25]

You need to update version_updater_win.cc and version_updater_mac.mm where
StatusCallback is invoked, similar to what you did in version_updater_basic.cc.

[weidongg, 2017/05/11 23:50:44]

Done.

       StatusCallback;
 
   // Used to show or hide the promote UI elements. Mac-only.
@@ -75,6 +84,14 @@ class VersionUpdater {
   virtual void CheckForUpdate(const StatusCallback& status_callback,
                               const PromoteCallback& promote_callback) = 0;
 
+  // Set the update over cellular target in preferences maintained by update
+  // engine. The preferences are latter used by update engine to match the given

[xiyuan, 2017/05/11 20:37:25]

nit: preferences -> |target_version| and |target_size| arguments
latter -> later

"preferences" usually refers to a Pref in PrefService in Chrome so avoid using
that for something else. 

[weidongg, 2017/05/11 23:50:44]

Ok, I see.

+  // target with the server head and to allow update over cellular to this given
+  // target.
+  virtual void SetUpdateOverCellularTarget(const StatusCallback& callback,
+                                           const std::string& target_version,
+                                           int64_t target_size) = 0;
+
 #if defined(OS_MACOSX)
   // Make updates available for all users.
   virtual void PromoteUpdater() const = 0;