re-use WebUIs

chrome/browser/ui/webui/help/help_handler.cc

Index: chrome/browser/ui/webui/help/help_handler.cc
diff --git a/chrome/browser/ui/webui/help/help_handler.cc b/chrome/browser/ui/webui/help/help_handler.cc
index 6f3a246be2f659665f21efb848e254bb3cae6b65..ab3d4b58c482c80e2dccb3ed9ef5b1e8db4e131f 100644
--- a/chrome/browser/ui/webui/help/help_handler.cc
+++ b/chrome/browser/ui/webui/help/help_handler.cc
@@ -185,6 +185,9 @@ void HelpHandler::GetLocalizedValues(DictionaryValue* localized_strings) {
 }
 
 void HelpHandler::RegisterMessages() {
+  registrar_.Add(this, chrome::NOTIFICATION_UPGRADE_RECOMMENDED,
+                 content::NotificationService::AllSources());

[stuartmorgan, 2012/04/24 09:12:20]

Why this change in ordering? If it's important, it should be commented.

[Evan Stade, 2012/04/24 17:52:40]

change in ordering? it's now in a different function. I can comment why, but the
reason for this (and many other changes) is that we may get OnPageLoaded
multiple times, and registering for the same notification multiple times =>
DCHECK.

(I did it this way instead of adding an |observing_| member because it's rare
that an upgrade recommendation notification would come through, so the page
loading will seldom lose the race against upgrade notification. In the other
cases, such as GpuInternals, the race was happening more often, causing lots of
console spew.)

[stuartmorgan, 2012/04/24 19:20:03]

Sorry, totally spaced on the elided lines in the review tool, and thought you
just moved it to the start of the same function.

+
   web_ui()->RegisterMessageCallback("onPageLoaded",
       base::Bind(&HelpHandler::OnPageLoaded, base::Unretained(this)));
   web_ui()->RegisterMessageCallback("relaunchNow",
@@ -248,9 +251,6 @@ void HelpHandler::OnPageLoaded(const ListValue* args) {
   version_updater_->GetReleaseChannel(
       base::Bind(&HelpHandler::OnReleaseChannel, base::Unretained(this)));
 #endif
-
-  registrar_.Add(this, chrome::NOTIFICATION_UPGRADE_RECOMMENDED,
-                 content::NotificationService::AllSources());
 }
 
 #if defined(OS_MACOSX)