Fix issue with the ordering of the most visited items.

This change allows the pinned items to work better after the history
has been cleared. Previously we were limited byt the amount of items
returned by the history. Now pinned items still show up even after the
history has been cleared.

Also, this change makes the filler items flow to the left of pinned
items as necessary.

BUG=20817

TEST=Launch chrome with a new profile. Navigate around so that you have
at least 5 non prepoluated thumbnails on the NTP. Pin the second and
the fifth item. Now clear your history. The pinned items should stay in
place and the fillers should flow around them.

Review URL: http://codereview.chromium.org/184001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25229 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 48 insertions, 34 deletions

diff --git a/chrome/browser/dom_ui/new_tab_ui.cc b/chrome/browser/dom_ui/new_tab_ui.cc
index 3f495bc..95b976d 100644
--- a/chrome/browser/dom_ui/new_tab_ui.cc
+++ b/chrome/browser/dom_ui/new_tab_ui.cc
@@ -473,7 +473,7 @@ void IncognitoTabHTMLSource::StartDataRequest(const std::string& path,
 ///////////////////////////////////////////////////////////////////////////////
 // MostVisitedPage
 
-// This struct is used when getting the prepopulated pages in case the user
+// This struct is used when getting the pre-populated pages in case the user
 // hasn't filled up his most visited pages.
 struct MostVisitedPage {
   std::wstring title;
@@ -788,21 +788,31 @@ void MostVisitedHandler::OnSegmentUsageAvailable(
 
   size_t data_index = 0;
   size_t output_index = 0;
+  size_t pre_populated_index = 0;
   const size_t pages_count = NewTabUI::UseOldNewTabPage() ?
       kOldMostVisitedPages : kMostVisitedPages;
-  while (output_index < pages_count && data_index < data->size()) {
+  static std::vector<MostVisitedPage> pre_populated_pages =
+        MostVisitedHandler::GetPrePopulatedPages();
+
+  while (output_index < pages_count) {
+    bool found = false;
     bool pinned = false;
     GURL url;
     string16 title;
     std::string pinned_url;
     std::string pinned_title;
+    GURL favicon_url;
+    GURL thumbnail_url;
 
     if (MostVisitedHandler::GetPinnedURLAtIndex(output_index, &pinned_url,
                                                 &pinned_title)) {
       url = GURL(pinned_url);
       title = UTF8ToUTF16(pinned_title);
       pinned = true;
-    } else {
+      found = true;
+    }
+
+    while (!found && data_index < data->size()) {
       const PageUsageData& page = *(*data)[data_index];
       data_index++;
       url = page.GetURL();
@@ -813,47 +823,51 @@ void MostVisitedHandler::OnSegmentUsageAvailable(
         continue;
 
       title = page.GetTitle();
+      found = true;
+    }
+
+    while (!found && pre_populated_index < pre_populated_pages.size()) {
+      MostVisitedPage page = pre_populated_pages[pre_populated_index++];
+      std::wstring key = GetDictionaryKeyForURL(page.url.spec());
+      if (pinned_urls_->HasKey(key) || url_blacklist_->HasKey(key) ||
+          seen_urls.find(page.url) != seen_urls.end())
+        continue;
+
+      title = WideToUTF16(page.title);
+      url = page.url;
+      favicon_url = page.favicon_url;
+      thumbnail_url = page.thumbnail_url;
+      found = true;
     }
 
-    // Found a page.
-    DictionaryValue* page_value = new DictionaryValue();
-    SetURLTitleAndDirection(page_value, title, url);
-    page_value->SetBoolean(L"pinned", pinned);
-    pages_value.Append(page_value);
+    if (found) {
+      // Add fillers as needed.
+      while (pages_value.GetSize() < output_index) {
+        DictionaryValue* filler_value = new DictionaryValue();
+        filler_value->SetBoolean(L"filler", true);
+        pages_value.Append(filler_value);
+      }
+
+      DictionaryValue* page_value = new DictionaryValue();
+      SetURLTitleAndDirection(page_value, title, url);
+      page_value->SetBoolean(L"pinned", pinned);
+      if (!thumbnail_url.is_empty())
+        page_value->SetString(L"thumbnailUrl", thumbnail_url.spec());
+      if (!favicon_url.is_empty())
+        page_value->SetString(L"faviconUrl", favicon_url.spec());
+      pages_value.Append(page_value);
+      most_visited_urls_.push_back(url);
+      seen_urls.insert(url);
+    }
     output_index++;
-    most_visited_urls_.push_back(url);
-    seen_urls.insert(url);
   }
 
   // If we found no pages we treat this as the first run.
   FundamentalValue first_run(NewTabHTMLSource::first_run() &&
-                             pages_value.GetSize() == 0);
+      pages_value.GetSize() == pre_populated_pages.size());
   // but first_run should only be true once.
   NewTabHTMLSource::set_first_run(false);
 
-  // If we have less than pages_count we add some predetermined pages.
-  if (pages_value.GetSize() < pages_count) {
-    static std::vector<MostVisitedPage> pages =
-        MostVisitedHandler::GetPrePopulatedPages();
-    for (std::vector<MostVisitedPage>::const_iterator it = pages.begin();
-        it != pages.end() && pages_value.GetSize() < pages_count;
-        ++it) {
-      MostVisitedPage page = *it;
-      std::wstring key = GetDictionaryKeyForURL(page.url.spec());
-      if (!pinned_urls_->HasKey(key) && !url_blacklist_->HasKey(key) &&
-          seen_urls.find(page.url) == seen_urls.end()) {
-        DictionaryValue* page_value = new DictionaryValue();
-        SetURLTitleAndDirection(page_value, WideToUTF16(page.title), page.url);
-        page_value->SetBoolean(L"pinned", false);
-        page_value->SetString(L"thumbnailUrl", page.thumbnail_url.spec());
-        page_value->SetString(L"faviconUrl", page.favicon_url.spec());
-        pages_value.Append(page_value);
-        most_visited_urls_.push_back(page.url);
-        seen_urls.insert(page.url);
-      }
-    }
-  }
-
   dom_ui_->CallJavascriptFunction(L"mostVisitedPages", pages_value, first_run);
 }