Most visited thumbnails and favicons need id-based urls

Extends ThumbnailSouce and FaviconSource to serve requests of
the form:
  chrome-search://favicon/<id>
  chrome-search://thumb/<id>

BUG=180371
TEST=Manual, look at NTP Most Visited on 1993
R=sreeram@chromium.org

Review URL: https://codereview.chromium.org/12732005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187480 0039d316-1c4b-4281-b951-d872f2087c98

17 files changed, 485 insertions, 158 deletions

diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index 0adef54..0d736b6 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -15,6 +15,7 @@
 #include "chrome/browser/history/top_sites.h"
 #include "chrome/browser/instant/instant_ntp.h"
 #include "chrome/browser/instant/instant_overlay.h"
+#include "chrome/browser/instant/instant_service.h"
 #include "chrome/browser/instant/instant_service_factory.h"
 #include "chrome/browser/instant/instant_tab.h"
 #include "chrome/browser/instant/search.h"
@@ -196,6 +197,25 @@ void EnsureSearchTermsAreSet(content::WebContents* contents,
       NavigationEntryUpdated();
 }
 
+bool GetURLForMostVisitedItemId(Profile* profile,
+                                uint64 most_visited_item_id,
+                                GURL* url) {
+  InstantService* instant_service =
+      InstantServiceFactory::GetForProfile(profile);
+  if (!instant_service)
+    return false;
+  return instant_service->GetURLForMostVisitedItemId(most_visited_item_id, url);
+}
+
+// Creates a new restriced id if one is not found.
+size_t GetMostVisitedItemIDForURL(Profile* profile, const GURL& url) {
+  InstantService* instant_service =
+      InstantServiceFactory::GetForProfile(profile);
+  if (!instant_service)
+    return 0;
+  return instant_service->AddURL(url);
+}
+
 }  // namespace
 
 InstantController::InstantController(chrome::BrowserInstantController* browser,
@@ -869,20 +889,26 @@ void InstantController::ClearDebugEvents() {
   debug_events_.clear();
 }
 
-void InstantController::DeleteMostVisitedItem(const GURL& url) {
+void InstantController::DeleteMostVisitedItem(uint64 most_visited_item_id) {
   history::TopSites* top_sites = browser_->profile()->GetTopSites();
   if (!top_sites)
     return;
 
-  top_sites->AddBlacklistedURL(url);
+  GURL url;
+  if (GetURLForMostVisitedItemId(browser_->profile(),
+                                 most_visited_item_id, &url))
+    top_sites->AddBlacklistedURL(url);
 }
 
-void InstantController::UndoMostVisitedDeletion(const GURL& url) {
+void InstantController::UndoMostVisitedDeletion(uint64 most_visited_item_id) {
   history::TopSites* top_sites = browser_->profile()->GetTopSites();
   if (!top_sites)
     return;
 
-  top_sites->RemoveBlacklistedURL(url);
+  GURL url;
+  if (GetURLForMostVisitedItemId(browser_->profile(),
+                                 most_visited_item_id, &url))
+    top_sites->RemoveBlacklistedURL(url);
 }
 
 void InstantController::UndoAllMostVisitedDeletions() {
@@ -1469,11 +1495,13 @@ void InstantController::RequestMostVisitedItems() {
 
 void InstantController::OnMostVisitedItemsReceived(
     const history::MostVisitedURLList& data) {
-  std::vector<MostVisitedItem> most_visited_items;
+  std::vector<InstantMostVisitedItem> most_visited_items;
   for (size_t i = 0; i < data.size(); i++) {
     const history::MostVisitedURL& url = data[i];
 
-    MostVisitedItem item;
+    InstantMostVisitedItem item;
+    item.most_visited_item_id = GetMostVisitedItemIDForURL(browser_->profile(),
+                                                           url.url);
     item.url = url.url;
     item.title = url.title;
 
@@ -1483,7 +1511,7 @@ void InstantController::OnMostVisitedItemsReceived(
 }
 
 void InstantController::SendMostVisitedItems(
-    const std::vector<MostVisitedItem>& items) {
+    const std::vector<InstantMostVisitedItem>& items) {
   if (overlay_)
     overlay_->SendMostVisitedItems(items);
   if (ntp_)
diff --git a/chrome/browser/instant/instant_controller.h b/chrome/browser/instant/instant_controller.h
index 64a9b06..cca84ff0 100644
--- a/chrome/browser/instant/instant_controller.h
+++ b/chrome/browser/instant/instant_controller.h
@@ -249,11 +249,11 @@ class InstantController : public InstantPage::Delegate,
 
   // Invoked by the InstantLoader when the Instant page wants to delete a
   // Most Visited item.
-  virtual void DeleteMostVisitedItem(const GURL& url) OVERRIDE;
+  virtual void DeleteMostVisitedItem(uint64 most_visited_item_id) OVERRIDE;
 
   // Invoked by the InstantLoader when the Instant page wants to undo a
   // Most Visited deletion.
-  virtual void UndoMostVisitedDeletion(const GURL& url) OVERRIDE;
+  virtual void UndoMostVisitedDeletion(uint64 most_visited_item_id) OVERRIDE;
 
   // Invoked by the InstantLoader when the Instant page wants to undo all
   // Most Visited deletions.
@@ -347,7 +347,7 @@ class InstantController : public InstantPage::Delegate,
 
   // Sends a collection of MostVisitedItems to the renderer process via
   // the appropriate InstantPage subclass.
-  void SendMostVisitedItems(const std::vector<MostVisitedItem>& items);
+  void SendMostVisitedItems(const std::vector<InstantMostVisitedItem>& items);
 
   chrome::BrowserInstantController* const browser_;
 
diff --git a/chrome/browser/instant/instant_io_context.cc b/chrome/browser/instant/instant_io_context.cc
index a4ab4fd..e2199d6 100644
--- a/chrome/browser/instant/instant_io_context.cc
+++ b/chrome/browser/instant/instant_io_context.cc
@@ -7,6 +7,7 @@
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/browser/resource_request_info.h"
+#include "googleurl/src/gurl.h"
 #include "net/url_request/url_request.h"
 
 using content::BrowserThread;
@@ -21,6 +22,15 @@ InstantIOContext* GetDataForResourceContext(
       context, InstantIOContext::kInstantIOContextKeyName);
 }
 
+InstantIOContext* GetDataForRequest(const net::URLRequest* request) {
+  const content::ResourceRequestInfo* info =
+      content::ResourceRequestInfo::ForRequest(request);
+  if (!info)
+    return NULL;
+
+  return GetDataForResourceContext(info->GetContext());
+}
+
 }  // namespace
 
 const char InstantIOContext::kInstantIOContextKeyName[] = "instant_io_context";
@@ -65,14 +75,38 @@ void InstantIOContext::ClearInstantProcessesOnIO(
 }
 
 // static
+void InstantIOContext::AddMostVisitedItemIDOnIO(
+    scoped_refptr<InstantIOContext> instant_io_context,
+    uint64 most_visited_item_id, const GURL& url) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  instant_io_context->most_visited_item_id_to_url_map_[most_visited_item_id] =
+      url;
+}
+
+// static
+void InstantIOContext::DeleteMostVisitedURLsOnIO(
+    scoped_refptr<InstantIOContext> instant_io_context,
+    std::vector<uint64> deleted_ids, bool all_history) {
+  if (all_history) {
+    instant_io_context->most_visited_item_id_to_url_map_.clear();
+    return;
+  }
+
+  for (size_t i = 0; i < deleted_ids.size(); ++i) {
+    instant_io_context->most_visited_item_id_to_url_map_.erase(
+        instant_io_context->most_visited_item_id_to_url_map_.find(
+            deleted_ids[i]));
+  }
+}
+
+// static
 bool InstantIOContext::ShouldServiceRequest(const net::URLRequest* request) {
   const content::ResourceRequestInfo* info =
       content::ResourceRequestInfo::ForRequest(request);
   if (!info)
     return false;
 
-  InstantIOContext* instant_io_context =
-      GetDataForResourceContext(info->GetContext());
+  InstantIOContext* instant_io_context = GetDataForRequest(request);
   if (!instant_io_context)
     return false;
 
@@ -84,7 +118,34 @@ bool InstantIOContext::ShouldServiceRequest(const net::URLRequest* request) {
   return false;
 }
 
+// static
+bool InstantIOContext::GetURLForMostVisitedItemId(
+    const net::URLRequest* request,
+    uint64 most_visited_item_id,
+    GURL* url) {
+  InstantIOContext* instant_io_context = GetDataForRequest(request);
+  if (!instant_io_context) {
+    *url = GURL();
+    return false;
+  }
+
+  return instant_io_context->GetURLForMostVisitedItemId(most_visited_item_id,
+                                                        url);
+}
+
 bool InstantIOContext::IsInstantProcess(int process_id) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return process_ids_.count(process_id) != 0;
 }
+
+bool InstantIOContext::GetURLForMostVisitedItemId(uint64 most_visited_item_id,
+                                                  GURL* url) {
+  std::map<uint64, GURL>::iterator it =
+      most_visited_item_id_to_url_map_.find(most_visited_item_id);
+  if (it != most_visited_item_id_to_url_map_.end()) {
+    *url = it->second;
+    return true;
+  }
+  *url = GURL();
+  return false;
+}
diff --git a/chrome/browser/instant/instant_io_context.h b/chrome/browser/instant/instant_io_context.h
index 26b9a56..99b805c 100644
--- a/chrome/browser/instant/instant_io_context.h
+++ b/chrome/browser/instant/instant_io_context.h
@@ -5,11 +5,15 @@
 #ifndef CHROME_BROWSER_INSTANT_INSTANT_IO_CONTEXT_
 #define CHROME_BROWSER_INSTANT_INSTANT_IO_CONTEXT_
 
+#include <map>
 #include <set>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 
+class GURL;
+
 namespace content {
 class ResourceContext;
 }
@@ -46,10 +50,28 @@ class InstantIOContext : public base::RefCountedThreadSafe<InstantIOContext> {
   static void ClearInstantProcessesOnIO(
       scoped_refptr<InstantIOContext> instant_io_context);
 
+  // Associates the |most_visited_item_id| with the |url|.
+  static void AddMostVisitedItemIDOnIO(
+      scoped_refptr<InstantIOContext> instant_io_context,
+      uint64 most_visited_item_id, const GURL& url);
+
+  // Deletes the Most Visited item IDs contained in |deleted_ids| from the url
+  // mapping.  If |all_history| is true, then ignores |deleted_ids| and
+  // deletes all mappings.
+  static void DeleteMostVisitedURLsOnIO(
+      scoped_refptr<InstantIOContext> instant_io_context,
+      std::vector<uint64> deleted_ids, bool all_history);
+
   // Determine if this chrome-search: request is coming from an Instant render
   // process.
   static bool ShouldServiceRequest(const net::URLRequest* request);
 
+  // Returns true if the |most_visited_item_id| is known, and |url| is set.
+  // Returns false otherwise.
+  static bool GetURLForMostVisitedItemId(
+      const net::URLRequest* request,
+      uint64 most_visited_item_id, GURL* url);
+
  protected:
    virtual ~InstantIOContext();
 
@@ -60,11 +82,18 @@ class InstantIOContext : public base::RefCountedThreadSafe<InstantIOContext> {
   // |process_ids_|.
   bool IsInstantProcess(int process_id) const;
 
+  bool GetURLForMostVisitedItemId(uint64 most_visited_item_id, GURL* url);
+
   // The process IDs associated with Instant processes.  Mirror of the process
   // IDs in InstantService.  Duplicated here for synchronous access on the IO
   // thread.
   std::set<int> process_ids_;
 
+  // The Most Visited item IDs map associated with Instant processes.  Mirror of
+  // the Most Visited item ID map in InstantService.  Duplicated here for
+  // synchronous access on the IO thread.
+  std::map<uint64, GURL> most_visited_item_id_to_url_map_;
+
   DISALLOW_COPY_AND_ASSIGN(InstantIOContext);
 };
 
diff --git a/chrome/browser/instant/instant_page.cc b/chrome/browser/instant/instant_page.cc
index 37496ee..c89521d 100644
--- a/chrome/browser/instant/instant_page.cc
+++ b/chrome/browser/instant/instant_page.cc
@@ -95,8 +95,8 @@ void InstantPage::KeyCaptureChanged(bool is_key_capture_enabled) {
 }
 
 void InstantPage::SendMostVisitedItems(
-    const std::vector<MostVisitedItem>& items) {
-  Send(new ChromeViewMsg_InstantMostVisitedItemsChanged(routing_id(), items));
+    const std::vector<InstantMostVisitedItem>& items) {
+  Send(new ChromeViewMsg_SearchBoxMostVisitedItemsChanged(routing_id(), items));
 }
 
 InstantPage::InstantPage(Delegate* delegate)
@@ -173,11 +173,11 @@ bool InstantPage::OnMessageReceived(const IPC::Message& message) {
                         OnStopCapturingKeyStrokes);
     IPC_MESSAGE_HANDLER(ChromeViewHostMsg_SearchBoxNavigate,
                         OnSearchBoxNavigate);
-    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_InstantDeleteMostVisitedItem,
+    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_SearchBoxDeleteMostVisitedItem,
                         OnDeleteMostVisitedItem);
-    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_InstantUndoMostVisitedDeletion,
+    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_SearchBoxUndoMostVisitedDeletion,
                         OnUndoMostVisitedDeletion);
-    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_InstantUndoAllMostVisitedDeletions,
+    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_SearchBoxUndoAllMostVisitedDeletions,
                         OnUndoAllMostVisitedDeletions);
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ -270,12 +270,12 @@ void InstantPage::OnSearchBoxNavigate(int page_id,
   }
 }
 
-void InstantPage::OnDeleteMostVisitedItem(const GURL& url) {
-  delegate_->DeleteMostVisitedItem(url);
+void InstantPage::OnDeleteMostVisitedItem(uint64 most_visited_item_id) {
+  delegate_->DeleteMostVisitedItem(most_visited_item_id);
 }
 
-void InstantPage::OnUndoMostVisitedDeletion(const GURL& url) {
-  delegate_->UndoMostVisitedDeletion(url);
+void InstantPage::OnUndoMostVisitedDeletion(uint64 most_visited_item_id) {
+  delegate_->UndoMostVisitedDeletion(most_visited_item_id);
 }
 
 void InstantPage::OnUndoAllMostVisitedDeletions() {
diff --git a/chrome/browser/instant/instant_page.h b/chrome/browser/instant/instant_page.h
index 024d44b..15c8fe4 100644
--- a/chrome/browser/instant/instant_page.h
+++ b/chrome/browser/instant/instant_page.h
@@ -90,10 +90,10 @@ class InstantPage : public content::WebContentsObserver {
                                WindowOpenDisposition disposition) = 0;
 
     // Called when the SearchBox wants to delete a Most Visited item.
-    virtual void DeleteMostVisitedItem(const GURL& url) = 0;
+    virtual void DeleteMostVisitedItem(uint64 most_visited_item_id) = 0;
 
     // Called when the SearchBox wants to undo a Most Visited deletion.
-    virtual void UndoMostVisitedDeletion(const GURL& url) = 0;
+    virtual void UndoMostVisitedDeletion(uint64 most_visited_item_id) = 0;
 
     // Called when the SearchBox wants to undo all Most Visited deletions.
     virtual void UndoAllMostVisitedDeletions() = 0;
@@ -171,7 +171,7 @@ class InstantPage : public content::WebContentsObserver {
   void KeyCaptureChanged(bool is_key_capture_enabled);
 
   // Tells the page about new Most Visited data.
-  void SendMostVisitedItems(const std::vector<MostVisitedItem>& items);
+  void SendMostVisitedItems(const std::vector<InstantMostVisitedItem>& items);
 
  protected:
   explicit InstantPage(Delegate* delegate);
@@ -228,8 +228,8 @@ class InstantPage : public content::WebContentsObserver {
                            const GURL& url,
                            content::PageTransition transition,
                            WindowOpenDisposition disposition);
-  void OnDeleteMostVisitedItem(const GURL& url);
-  void OnUndoMostVisitedDeletion(const GURL& url);
+  void OnDeleteMostVisitedItem(uint64 most_visited_item_id);
+  void OnUndoMostVisitedDeletion(uint64 most_visited_item_id);
   void OnUndoAllMostVisitedDeletions();
 
   Delegate* const delegate_;
diff --git a/chrome/browser/instant/instant_service.cc b/chrome/browser/instant/instant_service.cc
index 3c8a6b2..9482a8f 100644
--- a/chrome/browser/instant/instant_service.cc
+++ b/chrome/browser/instant/instant_service.cc
@@ -4,7 +4,10 @@
 
 #include "chrome/browser/instant/instant_service.h"
 
+#include "base/strings/string_number_conversions.h"
+#include "chrome/browser/history/history_notifications.h"
 #include "chrome/browser/instant/instant_io_context.h"
+#include "chrome/browser/instant/instant_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/ntp/thumbnail_source.h"
 #include "chrome/common/chrome_notification_types.h"
@@ -13,11 +16,29 @@
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/url_data_source.h"
+#include "googleurl/src/gurl.h"
+#include "net/url_request/url_request.h"
 
 using content::BrowserThread;
 
+namespace {
+
+// Copies deleted urls out of the history data structure |details| into a
+// straight vector of GURLs.
+void HistoryDetailsToDeletedURLs(const history::URLsDeletedDetails& details,
+                                 std::vector<GURL>* deleted_urls) {
+  for (history::URLRows::const_iterator it = details.rows.begin();
+       it != details.rows.end();
+       ++it) {
+    deleted_urls->push_back(it->url());
+  }
+}
+
+}  // namespace
+
 InstantService::InstantService(Profile* profile)
-    : profile_(profile) {
+    : profile_(profile),
+      last_most_visited_item_id_(0) {
   // Stub for unit tests.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI))
     return;
@@ -25,6 +46,9 @@ InstantService::InstantService(Profile* profile)
   registrar_.Add(this,
                  content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
                  content::NotificationService::AllSources());
+  registrar_.Add(this,
+                 chrome::NOTIFICATION_HISTORY_URLS_DELETED,
+                 content::NotificationService::AllSources());
 
   instant_io_context_ = new InstantIOContext();
 
@@ -41,6 +65,48 @@ InstantService::InstantService(Profile* profile)
 InstantService::~InstantService() {
 }
 
+// static
+const std::string InstantService::MaybeTranslateInstantPathOnUI(
+    Profile* profile, const std::string& path) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  InstantService* instant_service =
+      InstantServiceFactory::GetForProfile(profile);
+  if (!instant_service)
+    return path;
+
+  uint64 most_visited_item_id = 0;
+  if (base::StringToUint64(path, &most_visited_item_id)) {
+    GURL url;
+    if (instant_service->GetURLForMostVisitedItemId(most_visited_item_id, &url))
+      return url.spec();
+  }
+  return path;
+}
+
+const std::string InstantService::MaybeTranslateInstantPathOnIO(
+    const net::URLRequest* request, const std::string& path) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  uint64 most_visited_item_id = 0;
+  if (base::StringToUint64(path, &most_visited_item_id)) {
+    GURL url;
+    if (InstantIOContext::GetURLForMostVisitedItemId(request,
+                                                     most_visited_item_id,
+                                                     &url))
+      return url.spec();
+  }
+  return path;
+}
+
+// static
+bool InstantService::IsInstantPath(const GURL& url) {
+  // Strip leading slash.
+  std::string path = url.path().substr(1);
+
+  // Check that path is of Most Visited item ID form.
+  uint64 dummy = 0;
+  return base::StringToUint64(path, &dummy);
+}
+
 void InstantService::AddInstantProcess(int process_id) {
   process_ids_.insert(process_id);
 
@@ -56,6 +122,50 @@ bool InstantService::IsInstantProcess(int process_id) const {
   return process_ids_.find(process_id) != process_ids_.end();
 }
 
+uint64 InstantService::AddURL(const GURL& url) {
+  uint64 id = 0;
+  if (GetMostVisitedItemIDForURL(url, &id))
+    return id;
+
+  last_most_visited_item_id_++;
+  most_visited_item_id_to_url_map_[last_most_visited_item_id_] = url;
+  url_to_most_visited_item_id_map_[url] = last_most_visited_item_id_;
+
+  if (instant_io_context_) {
+    BrowserThread::PostTask(
+        BrowserThread::IO, FROM_HERE,
+        base::Bind(&InstantIOContext::AddMostVisitedItemIDOnIO,
+                   instant_io_context_, last_most_visited_item_id_, url));
+  }
+
+  return last_most_visited_item_id_;
+}
+
+bool InstantService::GetMostVisitedItemIDForURL(
+    const GURL& url,
+    uint64 *most_visited_item_id) {
+  std::map<GURL, uint64>::iterator it =
+      url_to_most_visited_item_id_map_.find(url);
+  if (it != url_to_most_visited_item_id_map_.end()) {
+    *most_visited_item_id = it->second;
+    return true;
+  }
+  *most_visited_item_id = 0;
+  return false;
+}
+
+bool InstantService::GetURLForMostVisitedItemId(uint64 most_visited_item_id,
+                                                GURL* url) {
+  std::map<uint64, GURL>::iterator it =
+      most_visited_item_id_to_url_map_.find(most_visited_item_id);
+  if (it != most_visited_item_id_to_url_map_.end()) {
+    *url = it->second;
+    return true;
+  }
+  *url = GURL();
+  return false;
+}
+
 void InstantService::Shutdown() {
   process_ids_.clear();
 
@@ -71,14 +181,59 @@ void InstantService::Shutdown() {
 void InstantService::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
-  DCHECK_EQ(type, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED);
-  int process_id = content::Source<content::RenderProcessHost>(source)->GetID();
-  process_ids_.erase(process_id);
+  switch (type) {
+    case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED: {
+      int process_id =
+          content::Source<content::RenderProcessHost>(source)->GetID();
+      process_ids_.erase(process_id);
+
+      if (instant_io_context_) {
+        BrowserThread::PostTask(
+            BrowserThread::IO, FROM_HERE,
+            base::Bind(&InstantIOContext::RemoveInstantProcessOnIO,
+                       instant_io_context_, process_id));
+      }
+      break;
+    }
+    case chrome::NOTIFICATION_HISTORY_URLS_DELETED: {
+      content::Details<history::URLsDeletedDetails> det(details);
+      std::vector<GURL> deleted_urls;
+      HistoryDetailsToDeletedURLs(*det.ptr(), &deleted_urls);
+
+      std::vector<uint64> deleted_ids;
+      if (det->all_history) {
+        url_to_most_visited_item_id_map_.clear();
+        most_visited_item_id_to_url_map_.clear();
+      } else {
+        DeleteHistoryURLs(deleted_urls, &deleted_ids);
+      }
+
+      if (instant_io_context_) {
+        BrowserThread::PostTask(
+            BrowserThread::IO, FROM_HERE,
+            base::Bind(&InstantIOContext::DeleteMostVisitedURLsOnIO,
+                       instant_io_context_, deleted_ids, det->all_history));
+      }
+      break;
+    }
+    default:
+      NOTREACHED() << "Unexpected notification type in InstantService.";
+  }
+}
 
-  if (instant_io_context_) {
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(&InstantIOContext::RemoveInstantProcessOnIO,
-                   instant_io_context_, process_id));
+void InstantService::DeleteHistoryURLs(const std::vector<GURL>& deleted_urls,
+                                       std::vector<uint64>* deleted_ids) {
+  for (std::vector<GURL>::const_iterator it = deleted_urls.begin();
+       it != deleted_urls.end();
+       ++it) {
+    std::map<GURL, uint64>::iterator item =
+        url_to_most_visited_item_id_map_.find(*it);
+    if (item != url_to_most_visited_item_id_map_.end()) {
+      uint64 most_visited_item_id = item->second;
+      url_to_most_visited_item_id_map_.erase(item);
+      most_visited_item_id_to_url_map_.erase(
+          most_visited_item_id_to_url_map_.find(most_visited_item_id));
+      deleted_ids->push_back(most_visited_item_id);
+    }
   }
 }
diff --git a/chrome/browser/instant/instant_service.h b/chrome/browser/instant/instant_service.h
index 4e08d89..bdb8a35 100644
--- a/chrome/browser/instant/instant_service.h
+++ b/chrome/browser/instant/instant_service.h
@@ -5,7 +5,9 @@
 #ifndef CHROME_BROWSER_INSTANT_INSTANT_SERVICE_H_
 #define CHROME_BROWSER_INSTANT_INSTANT_SERVICE_H_
 
+#include <map>
 #include <set>
+#include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
@@ -14,9 +16,14 @@
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
+class GURL;
 class InstantIOContext;
 class Profile;
 
+namespace net {
+class URLRequest;
+}
+
 // Tracks render process host IDs that are associated with Instant.
 class InstantService : public ProfileKeyedService,
                        public content::NotificationObserver {
@@ -24,6 +31,19 @@ class InstantService : public ProfileKeyedService,
   explicit InstantService(Profile* profile);
   virtual ~InstantService();
 
+  // A utility to translate an Instant path if it is of Most Visited item ID
+  // form.  If path is a Most Visited item ID and we have a URL for it, then
+  // this URL is returned in string form.  The |path| is a URL fragment
+  // corresponding to the path of url with the leading slash ("/") stripped.
+  // For example, chrome-search://favicon/72 would yield a |path| value of "72",
+  // and since 72 is a valid uint64 the path is translated to a valid url,
+  // "http://bingo.com/", say.
+  static const std::string MaybeTranslateInstantPathOnUI(
+      Profile* profile, const std::string& path);
+  static const std::string MaybeTranslateInstantPathOnIO(
+    const net::URLRequest* request, const std::string& path);
+  static bool IsInstantPath(const GURL& url);
+
   // Add, remove, and query RenderProcessHost IDs that are associated with
   // Instant processes.
   void AddInstantProcess(int process_id);
@@ -35,6 +55,19 @@ class InstantService : public ProfileKeyedService,
   }
 #endif
 
+  // If |url| is known the existing Most Visited item ID is returned.  Otherwise
+  // a new Most Visited item ID is associated with the |url| and returned.
+  uint64 AddURL(const GURL& url);
+
+  // If there is a mapping for the |url|, sets |most_visited_item_id| and
+  // returns true.
+  bool GetMostVisitedItemIDForURL(const GURL& url,
+                                  uint64* most_visited_item_id);
+
+  // If there is a mapping for the |most_visited_item_id|, sets |url| and
+  // returns true.
+  bool GetURLForMostVisitedItemId(uint64 most_visited_item_id, GURL* url);
+
  private:
   // Overridden from ProfileKeyedService:
   virtual void Shutdown() OVERRIDE;
@@ -44,11 +77,23 @@ class InstantService : public ProfileKeyedService,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Removes entries of each url in |deleted_urls| from the ID maps.  Or all
+  // IDs if |all_history| is true.  |deleted_ids| is filled with the newly
+  // deleted Most Visited item IDs.
+  void DeleteHistoryURLs(const std::vector<GURL>& deleted_urls,
+                         std::vector<uint64>* deleted_ids);
+
   Profile* const profile_;
 
   // The process ids associated with Instant processes.
   std::set<int> process_ids_;
 
+  // A mapping of Most Visited IDs to URLs.  Used to hide Most Visited and
+  // Favicon URLs from the Instant search provider.
+  uint64 last_most_visited_item_id_;
+  std::map<uint64, GURL> most_visited_item_id_to_url_map_;
+  std::map<GURL, uint64> url_to_most_visited_item_id_map_;
+
   content::NotificationRegistrar registrar_;
 
   scoped_refptr<InstantIOContext> instant_io_context_;
diff --git a/chrome/browser/ui/webui/favicon_source.cc b/chrome/browser/ui/webui/favicon_source.cc
index 3c86582..7414c43 100644
--- a/chrome/browser/ui/webui/favicon_source.cc
+++ b/chrome/browser/ui/webui/favicon_source.cc
@@ -10,6 +10,8 @@
 #include "chrome/browser/favicon/favicon_service_factory.h"
 #include "chrome/browser/history/top_sites.h"
 #include "chrome/browser/instant/instant_io_context.h"
+#include "chrome/browser/instant/instant_service.h"
+#include "chrome/browser/instant/instant_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/url_constants.h"
 #include "grit/locale_settings.h"
@@ -80,16 +82,22 @@ std::string FaviconSource::GetSource() {
 }
 
 void FaviconSource::StartDataRequest(
-    const std::string& path,
+    const std::string& raw_path,
     bool is_incognito,
     const content::URLDataSource::GotDataCallback& callback) {
   FaviconService* favicon_service =
       FaviconServiceFactory::GetForProfile(profile_, Profile::EXPLICIT_ACCESS);
-  if (!favicon_service || path.empty()) {
+  if (!favicon_service || raw_path.empty()) {
     SendDefaultResponse(callback);
     return;
   }
 
+  // Translate to regular path if |raw_path| is of the form
+  // chrome-search://favicon/<most_visited_item_id>, where
+  // "most_visited_item_id" is a uint64.
+  std::string path = InstantService::MaybeTranslateInstantPathOnUI(profile_,
+                                                                   raw_path);
+
   DCHECK_EQ(16, gfx::kFaviconSize);
   int size_in_dip = 16;
   ui::ScaleFactor scale_factor = ui::SCALE_FACTOR_100P;
@@ -219,8 +227,10 @@ bool FaviconSource::ShouldReplaceExistingSource() const {
 }
 
 bool FaviconSource::ShouldServiceRequest(const net::URLRequest* request) const {
-  if (request->url().SchemeIs(chrome::kChromeSearchScheme))
-    return InstantIOContext::ShouldServiceRequest(request);
+  if (request->url().SchemeIs(chrome::kChromeSearchScheme)) {
+    return InstantService::IsInstantPath(request->url()) &&
+        InstantIOContext::ShouldServiceRequest(request);
+  }
   return URLDataSource::ShouldServiceRequest(request);
 }
 
diff --git a/chrome/browser/ui/webui/ntp/thumbnail_source.cc b/chrome/browser/ui/webui/ntp/thumbnail_source.cc
index 706b760..0848da3 100644
--- a/chrome/browser/ui/webui/ntp/thumbnail_source.cc
+++ b/chrome/browser/ui/webui/ntp/thumbnail_source.cc
@@ -8,6 +8,8 @@
 #include "base/message_loop.h"
 #include "base/memory/ref_counted_memory.h"
 #include "chrome/browser/instant/instant_io_context.h"
+#include "chrome/browser/instant/instant_service.h"
+#include "chrome/browser/instant/instant_service_factory.h"
 #include "chrome/browser/thumbnails/thumbnail_service.h"
 #include "chrome/browser/thumbnails/thumbnail_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
@@ -17,9 +19,13 @@
 #include "net/url_request/url_request.h"
 #include "ui/base/resource/resource_bundle.h"
 
+using content::BrowserThread;
+
 // Set ThumbnailService now as Profile isn't thread safe.
 ThumbnailSource::ThumbnailSource(Profile* profile)
-    : thumbnail_service_(ThumbnailServiceFactory::GetForProfile(profile)) {
+    : thumbnail_service_(ThumbnailServiceFactory::GetForProfile(profile)),
+      current_request_(NULL),
+      profile_(profile) {
 }
 
 ThumbnailSource::~ThumbnailSource() {
@@ -30,9 +36,19 @@ std::string ThumbnailSource::GetSource() {
 }
 
 void ThumbnailSource::StartDataRequest(
-    const std::string& path,
+    const std::string& raw_path,
     bool is_incognito,
     const content::URLDataSource::GotDataCallback& callback) {
+  // Translate to regular path if |raw_path| is of the form
+  // chrome-search://favicon/<rid>, where rid is a uint64.
+  std::string path = raw_path;
+  if (BrowserThread::CurrentlyOn(BrowserThread::IO)) {
+    path = InstantService::MaybeTranslateInstantPathOnIO(
+        current_request_, raw_path);
+  } else if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+    path = InstantService::MaybeTranslateInstantPathOnUI(profile_, raw_path);
+  }
+
   scoped_refptr<base::RefCountedMemory> data;
   if (thumbnail_service_->GetPageThumbnail(GURL(path), &data)) {
     // We have the thumbnail.
@@ -40,6 +56,7 @@ void ThumbnailSource::StartDataRequest(
   } else {
     callback.Run(default_thumbnail_);
   }
+  current_request_ = NULL;
 }
 
 std::string ThumbnailSource::GetMimeType(const std::string&) const {
@@ -57,7 +74,10 @@ MessageLoop* ThumbnailSource::MessageLoopForRequestPath(
 
 bool ThumbnailSource::ShouldServiceRequest(
     const net::URLRequest* request) const {
-  if (request->url().SchemeIs(chrome::kChromeSearchScheme))
-    return InstantIOContext::ShouldServiceRequest(request);
+  current_request_ = request;
+  if (request->url().SchemeIs(chrome::kChromeSearchScheme)) {
+    return InstantService::IsInstantPath(request->url()) &&
+        InstantIOContext::ShouldServiceRequest(request);
+  }
   return URLDataSource::ShouldServiceRequest(request);
 }
diff --git a/chrome/browser/ui/webui/ntp/thumbnail_source.h b/chrome/browser/ui/webui/ntp/thumbnail_source.h
index dc98851..cbd82fa 100644
--- a/chrome/browser/ui/webui/ntp/thumbnail_source.h
+++ b/chrome/browser/ui/webui/ntp/thumbnail_source.h
@@ -49,6 +49,13 @@ class ThumbnailSource : public content::URLDataSource {
   // ThumbnailService.
   scoped_refptr<thumbnails::ThumbnailService> thumbnail_service_;
 
+  // Transient copy of the request in play. Valid between
+  // ShouldServiceRequest() and StartDataRequest().
+  mutable const net::URLRequest* current_request_;
+
+  // Only used when servicing requests on the UI thread.
+  Profile* const profile_;
+
   DISALLOW_COPY_AND_ASSIGN(ThumbnailSource);
 };
 
diff --git a/chrome/common/instant_types.h b/chrome/common/instant_types.h
index a7e748b..ae371c9 100644
--- a/chrome/common/instant_types.h
+++ b/chrome/common/instant_types.h
@@ -152,12 +152,17 @@ struct ThemeBackgroundInfo {
   uint16 image_height;
 };
 
-// A most visited item.
-struct MostVisitedItem {
-  // URL of the most visited page.
+struct InstantMostVisitedItem {
+  InstantMostVisitedItem() : most_visited_item_id(0) {}
+
+  // A private identifier used on the browser side when retrieving assets.
+  uint64 most_visited_item_id;
+
+  // The URL of the Most Visited item.
   GURL url;
 
-  // Title of the most visited page.
+  // The title of the Most Visited page.  May be empty, in which case the |url|
+  // is used as the title.
   string16 title;
 };
 
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index d7b4751..2e491af 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -167,7 +167,8 @@ IPC_STRUCT_TRAITS_BEGIN(InstantAutocompleteResult)
   IPC_STRUCT_TRAITS_MEMBER(relevance)
 IPC_STRUCT_TRAITS_END()
 
-IPC_STRUCT_TRAITS_BEGIN(MostVisitedItem)
+IPC_STRUCT_TRAITS_BEGIN(InstantMostVisitedItem)
+  IPC_STRUCT_TRAITS_MEMBER(most_visited_item_id)
   IPC_STRUCT_TRAITS_MEMBER(url)
   IPC_STRUCT_TRAITS_MEMBER(title)
 IPC_STRUCT_TRAITS_END()
@@ -342,16 +343,16 @@ IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxKeyCaptureChanged,
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxGrantChromeSearchAccessFromOrigin,
                     GURL /* origin_url */)
 
-IPC_MESSAGE_ROUTED1(ChromeViewMsg_InstantMostVisitedItemsChanged,
-                    std::vector<MostVisitedItem> /* items */)
+IPC_MESSAGE_ROUTED1(ChromeViewMsg_SearchBoxMostVisitedItemsChanged,
+                    std::vector<InstantMostVisitedItem> /* items */)
 
-IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_InstantDeleteMostVisitedItem,
-                    GURL /* url */)
+IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_SearchBoxDeleteMostVisitedItem,
+                    uint64 /* most_visited_item_id */)
 
-IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_InstantUndoMostVisitedDeletion,
-                    GURL /* url */)
+IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_SearchBoxUndoMostVisitedDeletion,
+                    uint64 /* most_visited_item_id */)
 
-IPC_MESSAGE_ROUTED0(ChromeViewHostMsg_InstantUndoAllMostVisitedDeletions)
+IPC_MESSAGE_ROUTED0(ChromeViewHostMsg_SearchBoxUndoAllMostVisitedDeletions)
 
 // Toggles visual muting of the render view area. This is on when a constrained
 // window is showing.
diff --git a/chrome/renderer/resources/extensions/searchbox_api.js b/chrome/renderer/resources/extensions/searchbox_api.js
index 466299e..24b2bc1 100644
--- a/chrome/renderer/resources/extensions/searchbox_api.js
+++ b/chrome/renderer/resources/extensions/searchbox_api.js
@@ -330,14 +330,14 @@ if (!chrome.embeddedSearch) {
       this.__defineGetter__('mostVisited', GetMostVisitedItemsWrapper);
       this.__defineGetter__('themeBackgroundInfo', GetThemeBackgroundInfo);
 
-      this.deleteMostVisitedItem = function(restrictId) {
-        DeleteMostVisitedItem(restrictId);
+      this.deleteMostVisitedItem = function(restrictedId) {
+        DeleteMostVisitedItem(restrictedId);
       };
       this.undoAllMostVisitedDeletions = function() {
         UndoAllMostVisitedDeletions();
       };
-      this.undoMostVisitedDeletion = function(restrictId) {
-        UndoMostVisitedDeletion(restrictId);
+      this.undoMostVisitedDeletion = function(restrictedId) {
+        UndoMostVisitedDeletion(restrictedId);
       };
       this.navigateContentWindow = function(destination, disposition) {
         NavigateNewTabPage(destination, disposition);
diff --git a/chrome/renderer/searchbox/searchbox.cc b/chrome/renderer/searchbox/searchbox.cc
index 37bd898..83a9bd5 100644
--- a/chrome/renderer/searchbox/searchbox.cc
+++ b/chrome/renderer/searchbox/searchbox.cc
@@ -12,16 +12,6 @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebSecurityPolicy.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 
-namespace {
-
-// Prefix for a thumbnail URL.
-const char kThumbnailUrlPrefix[] = "chrome-search://thumb/";
-
-// Prefix for a thumbnail URL.
-const char kFaviconUrlPrefix[] = "chrome-search://favicon/";
-
-}
-
 SearchBox::SearchBox(content::RenderView* render_view)
     : content::RenderViewObserver(render_view),
       content::RenderViewObserverTracker<SearchBox>(render_view),
@@ -33,8 +23,7 @@ SearchBox::SearchBox(content::RenderView* render_view)
       last_results_base_(0),
       is_key_capture_enabled_(false),
       display_instant_results_(false),
-      omnibox_font_size_(0),
-      last_most_visited_item_id_(0) {
+      omnibox_font_size_(0) {
 }
 
 SearchBox::~SearchBox() {
@@ -84,20 +73,19 @@ void SearchBox::NavigateToURL(const GURL& url,
       url, transition, disposition));
 }
 
-void SearchBox::DeleteMostVisitedItem(int most_visited_item_id) {
-  string16 url = MostVisitedItemIDToURL(most_visited_item_id);
-  render_view()->Send(new ChromeViewHostMsg_InstantDeleteMostVisitedItem(
-      render_view()->GetRoutingID(), GURL(url)));
+void SearchBox::DeleteMostVisitedItem(uint64 most_visited_item_id) {
+  render_view()->Send(new ChromeViewHostMsg_SearchBoxDeleteMostVisitedItem(
+      render_view()->GetRoutingID(), most_visited_item_id));
 }
 
-void SearchBox::UndoMostVisitedDeletion(int most_visited_item_id) {
-  string16 url = MostVisitedItemIDToURL(most_visited_item_id);
-  render_view()->Send(new ChromeViewHostMsg_InstantUndoMostVisitedDeletion(
-      render_view()->GetRoutingID(), GURL(url)));
+void SearchBox::UndoMostVisitedDeletion(uint64 most_visited_item_id) {
+  render_view()->Send(new ChromeViewHostMsg_SearchBoxUndoMostVisitedDeletion(
+      render_view()->GetRoutingID(), most_visited_item_id));
 }
 
 void SearchBox::UndoAllMostVisitedDeletions() {
-  render_view()->Send(new ChromeViewHostMsg_InstantUndoAllMostVisitedDeletions(
+  render_view()->Send(
+      new ChromeViewHostMsg_SearchBoxUndoAllMostVisitedDeletions(
       render_view()->GetRoutingID()));
 }
 
@@ -164,7 +152,7 @@ bool SearchBox::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(
         ChromeViewMsg_SearchBoxGrantChromeSearchAccessFromOrigin,
         OnGrantChromeSearchAccessFromOrigin)
-    IPC_MESSAGE_HANDLER(ChromeViewMsg_InstantMostVisitedItemsChanged,
+    IPC_MESSAGE_HANDLER(ChromeViewMsg_SearchBoxMostVisitedItemsChanged,
                         OnMostVisitedChanged)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ -352,7 +340,7 @@ void SearchBox::Reset() {
 }
 
 void SearchBox::OnMostVisitedChanged(
-    const std::vector<MostVisitedItem>& items) {
+    const std::vector<InstantMostVisitedItem>& items) {
   most_visited_items_ = items;
 
   if (render_view()->GetWebView() && render_view()->GetWebView()->mainFrame()) {
@@ -361,35 +349,7 @@ void SearchBox::OnMostVisitedChanged(
   }
 }
 
-const std::vector<MostVisitedItem>& SearchBox::GetMostVisitedItems() {
+const std::vector<InstantMostVisitedItem>&
+SearchBox::GetMostVisitedItems() const {
   return most_visited_items_;
 }
-
-int SearchBox::URLToMostVisitedItemID(string16 url) {
-  if (url_to_most_visited_item_id_map_[url])
-    return url_to_most_visited_item_id_map_[url];
-
-  last_most_visited_item_id_++;
-  url_to_most_visited_item_id_map_[url] = last_most_visited_item_id_;
-  most_visited_item_id_to_url_map_[last_most_visited_item_id_] = url;
-
-  return last_most_visited_item_id_;
-}
-
-string16 SearchBox::MostVisitedItemIDToURL(int most_visited_item_id) {
-  return most_visited_item_id_to_url_map_[most_visited_item_id];
-}
-
-string16 SearchBox::GenerateThumbnailUrl(int most_visited_item_id) {
-  std::ostringstream ostr;
-  ostr << kThumbnailUrlPrefix << most_visited_item_id;
-  GURL url = GURL(ostr.str());
-  return UTF8ToUTF16(url.spec());
-}
-
-string16 SearchBox::GenerateFaviconUrl(int most_visited_item_id) {
-  std::ostringstream ostr;
-  ostr << kFaviconUrlPrefix << most_visited_item_id;
-  GURL url = GURL(ostr.str());
-  return UTF8ToUTF16(url.spec());
-}
diff --git a/chrome/renderer/searchbox/searchbox.h b/chrome/renderer/searchbox/searchbox.h
index 9adc991..1882729 100644
--- a/chrome/renderer/searchbox/searchbox.h
+++ b/chrome/renderer/searchbox/searchbox.h
@@ -49,13 +49,14 @@ class SearchBox : public content::RenderViewObserver,
                      content::PageTransition transition,
                      WindowOpenDisposition disposition);
 
-  // Sends ChromeViewHostMsg_InstantDeleteMostVisitedItem to the browser.
-  void DeleteMostVisitedItem(int most_visited_item_id);
+  // Sends ChromeViewHostMsg_SearchBoxDeleteMostVisitedItem to the browser.
+  void DeleteMostVisitedItem(uint64 most_visited_item_id);
 
-  // Sends ChromeViewHostMsg_InstantUndoMostVisitedDeletion to the browser.
-  void UndoMostVisitedDeletion(int most_visited_item_id);
+  // Sends ChromeViewHostMsg_SearchBoxUndoMostVisitedDeletion to the browser.
+  void UndoMostVisitedDeletion(uint64 most_visited_item_id);
 
-  // Sends ChromeViewHostMsg_InstantUndoAllMostVisitedDeletions to the browser.
+  // Sends ChromeViewHostMsg_SearchBoxUndoAllMostVisitedDeletions to the
+  // browser.
   void UndoAllMostVisitedDeletions();
 
   const string16& query() const { return query_; }
@@ -82,13 +83,7 @@ class SearchBox : public content::RenderViewObserver,
   const ThemeBackgroundInfo& GetThemeBackgroundInfo();
 
   // Most Visited items.
-  const std::vector<MostVisitedItem>& GetMostVisitedItems();
-
-  // Secure Urls.
-  int URLToMostVisitedItemID(const string16 url);
-  string16 MostVisitedItemIDToURL(int most_visited_item_id);
-  string16 GenerateThumbnailUrl(int most_visited_item_id);
-  string16 GenerateFaviconUrl(int most_visited_item_id);
+  const std::vector<InstantMostVisitedItem>& GetMostVisitedItems() const;
 
  private:
   // Overridden from content::RenderViewObserver:
@@ -115,7 +110,7 @@ class SearchBox : public content::RenderViewObserver,
   void OnFontInformationReceived(const string16& omnibox_font,
                                  size_t omnibox_font_size);
   void OnGrantChromeSearchAccessFromOrigin(const GURL& origin_url);
-  void OnMostVisitedChanged(const std::vector<MostVisitedItem>& items);
+  void OnMostVisitedChanged(const std::vector<InstantMostVisitedItem>& items);
 
   // Returns the current zoom factor of the render view or 1 on failure.
   double GetZoom() const;
@@ -138,13 +133,7 @@ class SearchBox : public content::RenderViewObserver,
   bool display_instant_results_;
   string16 omnibox_font_;
   size_t omnibox_font_size_;
-  std::vector<MostVisitedItem> most_visited_items_;
-
-  // TODO(dcblack): Unify this logic to work with both Most Visited and
-  // history suggestions. http://crbug.com/175768
-  std::map<string16, int> url_to_most_visited_item_id_map_;
-  std::map<int, string16> most_visited_item_id_to_url_map_;
-  int last_most_visited_item_id_;
+  std::vector<InstantMostVisitedItem> most_visited_items_;
 
   DISALLOW_COPY_AND_ASSIGN(SearchBox);
 };
diff --git a/chrome/renderer/searchbox/searchbox_extension.cc b/chrome/renderer/searchbox/searchbox_extension.cc
index f456af0..25c4e09 100644
--- a/chrome/renderer/searchbox/searchbox_extension.cc
+++ b/chrome/renderer/searchbox/searchbox_extension.cc
@@ -63,6 +63,28 @@ void Dispatch(WebKit::WebFrame* frame, const WebKit::WebString& script) {
   frame->executeScript(WebKit::WebScriptSource(script));
 }
 
+v8::Handle<v8::String> GenerateThumbnailURL(uint64 most_visited_item_id) {
+  return UTF8ToV8String(
+      StringPrintf("chrome-search://thumb/%s",
+                   base::Uint64ToString(most_visited_item_id).c_str()));
+}
+
+v8::Handle<v8::String> GenerateFaviconURL(uint64 most_visited_item_id) {
+  return UTF8ToV8String(
+      StringPrintf("chrome-search://favicon/%s",
+                   base::Uint64ToString(most_visited_item_id).c_str()));
+}
+
+const GURL MostVisitedItemIDToURL(
+    const std::vector<InstantMostVisitedItem>& most_visited_items,
+    uint64 most_visited_item_id) {
+  for (size_t i = 0; i < most_visited_items.size(); ++i) {
+    if (most_visited_items[i].most_visited_item_id == most_visited_item_id)
+      return most_visited_items[i].url;
+  }
+  return GURL();
+}
+
 }  // namespace
 
 namespace extensions_v8 {
@@ -730,8 +752,9 @@ v8::Handle<v8::Value> SearchBoxExtensionWrapper::NavigateNewTabPage(
   GURL destination_url;
   content::PageTransition transition = content::PAGE_TRANSITION_TYPED;
   if (args[0]->IsNumber()) {
-    destination_url = GURL(SearchBox::Get(render_view)->MostVisitedItemIDToURL(
-        args[0]->Uint32Value()));
+    destination_url = MostVisitedItemIDToURL(
+        SearchBox::Get(render_view)->GetMostVisitedItems(),
+        args[0]->Uint32Value());
   } else {
     destination_url = GURL(V8ValueToUTF16(args[0]));
   }
@@ -931,20 +954,16 @@ v8::Handle<v8::Value> SearchBoxExtensionWrapper::ShowOverlay(
 v8::Handle<v8::Value> SearchBoxExtensionWrapper::GetMostVisitedItems(
     const v8::Arguments& args) {
   content::RenderView* render_view = GetRenderView();
-  if (!render_view) return v8::Undefined();
-
+  if (!render_view)
+    return v8::Undefined();
   DVLOG(1) << render_view << " GetMostVisitedItems";
 
-  const std::vector<MostVisitedItem>& items =
-      SearchBox::Get(render_view)->GetMostVisitedItems();
-  v8::Handle<v8::Array> items_array = v8::Array::New(items.size());
-  for (size_t i = 0; i < items.size(); ++i) {
-
-    const string16 url = UTF8ToUTF16(items[i].url.spec());
-    const string16 host = UTF8ToUTF16(items[i].url.host());
-    int most_visited_item_id =
-        SearchBox::Get(render_view)->URLToMostVisitedItemID(url);
+  const SearchBox* search_box = SearchBox::Get(render_view);
 
+  const std::vector<InstantMostVisitedItem>& instant_mv_items =
+      search_box->GetMostVisitedItems();
+  v8::Handle<v8::Array> v8_mv_items = v8::Array::New(instant_mv_items.size());
+  for (size_t i = 0; i < instant_mv_items.size(); ++i) {
     // We set the "dir" attribute of the title, so that in RTL locales, a LTR
     // title is rendered left-to-right and truncated from the right. For
     // example, the title of http://msdn.microsoft.com/en-us/default.aspx is
@@ -957,33 +976,31 @@ v8::Handle<v8::Value> SearchBoxExtensionWrapper::GetMostVisitedItems(
     // title will be rendered as "!Yahoo" if its "dir" attribute is not set to
     // "ltr".
     std::string direction;
-    if (base::i18n::StringContainsStrongRTLChars(items[i].title))
+    if (base::i18n::StringContainsStrongRTLChars(instant_mv_items[i].title))
       direction = kRTLHtmlTextDirection;
     else
       direction = kLTRHtmlTextDirection;
 
-    string16 title = items[i].title;
+    string16 title = instant_mv_items[i].title;
     if (title.empty())
-      title = url;
+      title = UTF8ToUTF16(instant_mv_items[i].url.spec());
 
     v8::Handle<v8::Object> item = v8::Object::New();
     item->Set(v8::String::New("rid"),
-              v8::Int32::New(most_visited_item_id));
+              v8::Int32::New(instant_mv_items[i].most_visited_item_id));
     item->Set(v8::String::New("thumbnailUrl"),
-              UTF16ToV8String(SearchBox::Get(render_view)->
-                              GenerateThumbnailUrl(most_visited_item_id)));
+              GenerateThumbnailURL(instant_mv_items[i].most_visited_item_id));
     item->Set(v8::String::New("faviconUrl"),
-              UTF16ToV8String(SearchBox::Get(render_view)->
-                              GenerateFaviconUrl(most_visited_item_id)));
+              GenerateFaviconURL(instant_mv_items[i].most_visited_item_id));
     item->Set(v8::String::New("title"),
               UTF16ToV8String(title));
-    item->Set(v8::String::New("domain"), UTF16ToV8String(host));
-    item->Set(v8::String::New("direction"),
-              UTF8ToV8String(direction));
+    item->Set(v8::String::New("domain"),
+              UTF8ToV8String(instant_mv_items[i].url.host()));
+    item->Set(v8::String::New("direction"), UTF8ToV8String(direction));
 
-    items_array->Set(i, item);
+    v8_mv_items->Set(i, item);
   }
-  return items_array;
+  return v8_mv_items;
 }
 
 // static