Implement coarse "on demand" functionality for update checks.

chrome/browser/component_updater/component_updater_service.cc

Index: chrome/browser/component_updater/component_updater_service.cc
diff --git a/chrome/browser/component_updater/component_updater_service.cc b/chrome/browser/component_updater/component_updater_service.cc
index 367ff6e7d5ec326a0ca0d6807f36c76b4e5d3cd2..124c509f3f124e0697ffbccecf01803b3d0a7423 100644
--- a/chrome/browser/component_updater/component_updater_service.cc
+++ b/chrome/browser/component_updater/component_updater_service.cc
@@ -63,11 +63,15 @@ const CrxComponent::UrlSource kManifestSources[] = {
 bool AddQueryString(const std::string& id,
                     const std::string& version,
                     const std::string& fingerprint,
+                    bool ondemand,
                     size_t limit,
                     std::string* query) {
   std::string additional =
-      base::StringPrintf("id=%s&v=%s&fp=%s&uc",
-                         id.c_str(), version.c_str(), fingerprint.c_str());
+      base::StringPrintf("id=%s&v=%s&fp=%s&uc%s",
+                         id.c_str(),
+                         version.c_str(),
+                         fingerprint.c_str(),
+                         ondemand ? "&installsource=ondemand" : "");
   additional = "x=" + net::EscapeQueryParamValue(additional, true);
   if ((additional.size() + query->size() + 1) > limit)
     return false;
@@ -575,7 +579,9 @@ bool CrxUpdateService::AddItemToUpdateCheck(CrxUpdateItem* item,
   if (!AddQueryString(item->id,
                       item->component.version.GetString(),
                       item->component.fingerprint,
-                      config_->UrlSizeLimit(), query))
+                      requested_work_items_.count(item),

[Sorin Jianu, 2013/06/24 17:25:57]

I would consider using a
const bool is_ondemand = requested_work_items_.count(item);

The code is efficient as before, with the added benefit of making explicit what
the value of the expression means. A brief code comment to explain how the
feature is intended to work would be useful as well.

[asargent_no_longer_on_chrome, 2013/06/24 17:34:51]

This is a good suggestion. A slightly more compact pattern we sometimes use as
well is to just include a comment inline with the argument you're passing, e.g.


requested_work_items_.count(item), // is_ondemand


Either way would be fine. 

[waffles, 2013/06/24 17:39:30]

Done.

+                      config_->UrlSizeLimit(),
+                      query))
     return false;
 
   item->status = CrxUpdateItem::kChecking;