Recreate the loader as soon as it is deleted and ensure that it does not become stale.

chrome/browser/instant/instant_controller.cc

Index: chrome/browser/instant/instant_controller.cc
diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index 6133e45715c52918198fc2d6094e374107683ec0..af356fc6054fb1c47634526524af3ebeccee522c 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -52,6 +52,10 @@ const int kUpdateBoundsDelayMS = 1000;
 // before we give up and blacklist it for the rest of the browsing session.
 const int kMaxInstantSupportFailures = 10;
 
+// If an instant page has not been used in this much time, it is reloaded so
+// that the page does not become stale.

[sreeram, 2012/08/22 17:39:35]

// If an Instant page has not been used in these many milliseconds, ...

[Shishir, 2012/08/23 18:26:33]

Done.

+const int kInstantRefreshIntervalMS = 3 * 3600 * 1000;

[sreeram, 2012/08/22 17:39:35]

Perhaps call this kStaleLoaderTimeoutMS?

[Shishir, 2012/08/23 18:26:33]

Done.

+
 std::string ModeToString(InstantController::Mode mode) {
   switch (mode) {
     case InstantController::INSTANT:  return "_Instant";
@@ -168,6 +172,9 @@ bool InstantController::Update(const AutocompleteMatch& match,
     return false;
   }
 
+  // Rechedule the instant loader refresh.
+  ScheduleLoaderRefresh();
+
   // The presence of any suggested_text implies verbatim.
   DCHECK(suggested_text->empty() || verbatim)
       << user_text << "|" << *suggested_text;
@@ -264,6 +271,11 @@ TabContents* InstantController::CommitCurrentPreview(InstantCommitType type) {
   preview->web_contents()->GetController().CopyStateFromAndPrune(
       &active_tab->web_contents()->GetController());
   delegate_->CommitInstant(preview);
+
+  // Try to create another loader immediately so that it is ready for the next
+  // user interaction.
+  ResetLoaderWithDefaultUrlAndCurrentTab();
+
   return preview;
 }
 
@@ -398,23 +410,7 @@ void InstantController::OnAutocompleteLostFocus(
 }
 
 void InstantController::OnAutocompleteGotFocus() {
-  const TabContents* active_tab = delegate_->GetActiveTabContents();
-
-  // We could get here with no active tab if the Browser is closing.
-  if (!active_tab)
-    return;
-
-  // Since we don't have any autocomplete match to work with, we'll just use
-  // the default search provider's Instant URL.
-  const TemplateURL* template_url =
-      TemplateURLServiceFactory::GetForProfile(active_tab->profile())->
-                                 GetDefaultSearchProvider();
-
-  std::string instant_url;
-  if (!GetInstantURL(template_url, &instant_url))
-    return;
-
-  ResetLoader(instant_url, active_tab);
+  ResetLoaderWithDefaultUrlAndCurrentTab();
 }
 
 bool InstantController::commit_on_pointer_release() const {
@@ -506,18 +502,63 @@ void InstantController::InstantLoaderContentsFocused(InstantLoader* loader) {
 #endif
 }
 
+void InstantController::CreateLoader(const std::string& instant_url,
+                                     const TabContents* active_tab) {
+  DCHECK(!loader_.get());
+  loader_.reset(new InstantLoader(this, instant_url, active_tab));
+  loader_->Init();
+  ScheduleLoaderRefresh();
+  AddPreviewUsageForHistogram(mode_, PREVIEW_CREATED);
+}

[sreeram, 2012/08/22 17:39:35]

We don't need this method (CreateLoader) at all. We could just have these:

void ResetLoader(...) {
  if (GetPreviewContents() && ...)
    DeleteLoader();
  if (!GetPreviewContents()) {
    loader_.reset(...);
    loader_->Init();
    ResetStaleLoaderTimer();
    AddPreviewUsageForHistogram(...);
  }
}

void CreateDefaultLoader(...) {
  const TabContents* active_tab = ...;
  ...
  const TemplateURL* template_url = ...;
  ...
  ResetLoader(instant_url, active_tab);
}

void OnStaleLoader() {
  if (!is_showing_) {
    DeleteLoader();
    CreateDefaultLoader();
  }
}

void ResetStaleLoaderTimer() {
  stale_loader_timer_.Stop();
  stale_loader_timer_.Start(...);
}

[Shishir, 2012/08/23 18:26:33]

Done.

+
 void InstantController::ResetLoader(const std::string& instant_url,
                                     const TabContents* active_tab) {
   if (GetPreviewContents() && loader_->instant_url() != instant_url)
     DeleteLoader();
 
-  if (!GetPreviewContents()) {
-    loader_.reset(new InstantLoader(this, instant_url, active_tab));
-    loader_->Init();
-    AddPreviewUsageForHistogram(mode_, PREVIEW_CREATED);
+  if (!GetPreviewContents())
+    CreateLoader(instant_url, active_tab);
+}
+
+void InstantController::ResetLoaderWithDefaultUrlAndCurrentTab() {
+  const TabContents* active_tab = delegate_->GetActiveTabContents();
+
+  // We could get here with no active tab if the Browser is closing.
+  if (!active_tab)
+    return;
+
+  const TemplateURL* template_url =
+      TemplateURLServiceFactory::GetForProfile(active_tab->profile())->
+                                 GetDefaultSearchProvider();
+  std::string instant_url;
+  if (!GetInstantURL(template_url, &instant_url))
+    return;
+
+  ResetLoader(instant_url, active_tab);
+}
+
+void InstantController::ScheduleLoaderRefresh() {
+  if (loader_refresh_timer_.IsRunning()) {
+    loader_refresh_timer_.Reset();
+  } else {
+    loader_refresh_timer_.Start(
+        FROM_HERE,
+        base::TimeDelta::FromMilliseconds(kInstantRefreshIntervalMS), this,
+        &InstantController::RefreshLoader);
   }
 }
 
+void InstantController::RefreshLoader() {
+  // If the loader is showing, do not delete it, but reschedule a refresh.
+  if (is_showing_) {
+    ScheduleLoaderRefresh();
+    return;
+  }
+
+  DeleteLoader();
+  ResetLoaderWithDefaultUrlAndCurrentTab();
+}
+
 void InstantController::DeleteLoader() {
   Hide();
   last_full_text_.clear();
@@ -529,6 +570,7 @@ void InstantController::DeleteLoader() {
   url_for_history_ = GURL();
   if (GetPreviewContents())
     AddPreviewUsageForHistogram(mode_, PREVIEW_DELETED);
+  loader_refresh_timer_.Stop();
   loader_.reset();
 }