Fix the race condition on TopSites initialization.

Change TopSites::GetMostVisitedURLs to take a callback. This allows TopSites to wait for the results list from the TopSitesDatabase.

BUG=none
TEST=TopSitesTest

Review URL: http://codereview.chromium.org/2811028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51002 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 30 insertions, 13 deletions

diff --git a/chrome/browser/dom_ui/most_visited_handler.cc b/chrome/browser/dom_ui/most_visited_handler.cc
index 87fd109..c7d38cf 100644
--- a/chrome/browser/dom_ui/most_visited_handler.cc
+++ b/chrome/browser/dom_ui/most_visited_handler.cc
@@ -117,12 +117,7 @@ void MostVisitedHandler::RegisterMessages() {
 void MostVisitedHandler::HandleGetMostVisited(const Value* value) {
   if (!got_first_most_visited_request_) {
     // If our intial data is already here, return it.
-    if (pages_value_.get()) {
-      FundamentalValue first_run(IsFirstRun());
-      dom_ui_->CallJavascriptFunction(L"mostVisitedPages",
-                                      *(pages_value_.get()), first_run);
-      pages_value_.reset();
-    }
+    SendPagesValue();
     got_first_most_visited_request_ = true;
   } else {
     StartQueryForMostVisited();
@@ -151,12 +146,22 @@ void MostVisitedHandler::SetPagesValue(const
   }
 }
 
+void MostVisitedHandler::SendPagesValue() {
+  if (pages_value_.get()) {
+    FundamentalValue first_run(IsFirstRun());
+    dom_ui_->CallJavascriptFunction(L"mostVisitedPages",
+                                    *(pages_value_.get()), first_run);
+    pages_value_.reset();
+  }
+}
+
 void MostVisitedHandler::StartQueryForMostVisited() {
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kTopSites)) {
     // Use TopSites.
-    history::MostVisitedURLList top_urls =
-        dom_ui_->GetProfile()->GetTopSites()->GetMostVisitedURLs();
-    SetPagesValue(top_urls);
+    history::TopSites* ts = dom_ui_->GetProfile()->GetTopSites();
+    ts->GetMostVisitedURLs(
+        &topsites_consumer_,
+        NewCallback(this, &MostVisitedHandler::OnMostVisitedURLsAvailable));
     return;
   }
 
@@ -416,10 +421,15 @@ void MostVisitedHandler::OnSegmentUsageAvailable(
   }
 
   if (got_first_most_visited_request_) {
-    FundamentalValue first_run(IsFirstRun());
-    dom_ui_->CallJavascriptFunction(L"mostVisitedPages", *(pages_value_.get()),
-                                    first_run);
-    pages_value_.reset();
+    SendPagesValue();
+  }
+}
+
+void MostVisitedHandler::OnMostVisitedURLsAvailable(
+    const history::MostVisitedURLList& data) {
+  SetPagesValue(data);
+  if (got_first_most_visited_request_) {
+    SendPagesValue();
   }
 }
 
diff --git a/chrome/browser/dom_ui/most_visited_handler.h b/chrome/browser/dom_ui/most_visited_handler.h
index a44b5a6..1ace9fc 100644
--- a/chrome/browser/dom_ui/most_visited_handler.h
+++ b/chrome/browser/dom_ui/most_visited_handler.h
@@ -78,6 +78,9 @@ class MostVisitedHandler : public DOMMessageHandler,
   void OnSegmentUsageAvailable(CancelableRequestProvider::Handle handle,
                                std::vector<PageUsageData*>* data);
 
+  // Callback for TopSites.
+  void OnMostVisitedURLsAvailable(const history::MostVisitedURLList& data);
+
   // Puts the passed URL in the blacklist (so it does not show as a thumbnail).
   void BlacklistURL(const GURL& url);
 
@@ -95,6 +98,9 @@ class MostVisitedHandler : public DOMMessageHandler,
   // Sets pages_value_ from MostVisitedURLs.
   void SetPagesValue(const history::MostVisitedURLList& urls);
 
+  // Sends pages_value_ to the javascript side to and resets page_value_.
+  void SendPagesValue();
+
   // Returns true if we should treat this as the first run of the new tab page.
   bool IsFirstRun();
 
@@ -104,6 +110,7 @@ class MostVisitedHandler : public DOMMessageHandler,
 
   // Our consumer for the history service.
   CancelableRequestConsumerTSimple<PageUsageData*> cancelable_consumer_;
+  CancelableRequestConsumer topsites_consumer_;
 
   // The most visited URLs, in priority order.
   // Only used for matching up clicks on the page to which most visited entry