InstantExtended: fall back to offline NTP if Instant NTP not ready.

BUG=190190
COLLABORATOR=shishir@chromium.org

Review URL: https://chromiumcodereview.appspot.com/12578006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@191076 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 119 insertions, 64 deletions

diff --git a/chrome/browser/search/search.cc b/chrome/browser/search/search.cc
index b8c16dc..cf5a50f 100644
--- a/chrome/browser/search/search.cc
+++ b/chrome/browser/search/search.cc
@@ -55,6 +55,9 @@ const char kInstantExtendedActivationName[] = "instant";
 const InstantExtendedDefault kInstantExtendedActivationDefault =
     INSTANT_DEFAULT_ON;
 
+// Key for specifying local NTP beahvior trials.
+const char kLocalNTPFlagName[] = "local_ntp";
+
 // Constants for the field trial name and group prefix.
 const char kInstantExtendedFieldTrialName[] = "InstantExtended";
 const char kGroupNumberPrefix[] = "Group";
@@ -447,6 +450,24 @@ bool IsInstantEnabled(Profile* profile) {
   return GetInstantURL(profile, kDisableStartMargin).is_valid();
 }
 
+bool IsAggressiveLocalNTPFallbackEnabled() {
+  // Check the command-line/about:flags setting first, which should have
+  // precedence and allows the trial to not be reported (if it's never queried).
+  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kDisableInstantExtendedAPI) ||
+      command_line->HasSwitch(switches::kEnableInstantExtendedAPI)) {
+    return false;
+  }
+
+  FieldTrialFlags flags;
+  if (GetFieldTrialInfo(
+          base::FieldTrialList::FindFullName(kInstantExtendedFieldTrialName),
+          &flags, NULL)) {
+    return GetBoolValueForFlagWithDefault(kLocalNTPFlagName, false, flags);
+  }
+  return false;
+}
+
 void EnableInstantExtendedAPIForTesting() {
   CommandLine* cl = CommandLine::ForCurrentProcess();
   cl->AppendSwitch(switches::kEnableInstantExtendedAPI);
diff --git a/chrome/browser/search/search.h b/chrome/browser/search/search.h
index ee9dfb62..bec267e 100644
--- a/chrome/browser/search/search.h
+++ b/chrome/browser/search/search.h
@@ -105,6 +105,10 @@ GURL GetInstantURL(Profile* profile, int start_margin);
 // lead to an infinite recursion.
 bool IsInstantEnabled(Profile* profile);
 
+// Returns true if the aggressive local NTP fallback is enabled in field
+// trials.
+bool IsAggressiveLocalNTPFallbackEnabled();
+
 // -----------------------------------------------------
 // The following APIs are exposed for use in tests only.
 // -----------------------------------------------------
diff --git a/chrome/browser/ui/search/instant_controller.cc b/chrome/browser/ui/search/instant_controller.cc
index fd7f30d..e1e3551 100644
--- a/chrome/browser/ui/search/instant_controller.cc
+++ b/chrome/browser/ui/search/instant_controller.cc
@@ -277,7 +277,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
   // DCHECKs below because |user_text| and |full_text| have different semantics
   // when keyword search is in effect.
   if (is_keyword_search) {
-    if (instant_tab_)
+    if (UseInstantTabToShowSuggestions())
       instant_tab_->Update(string16(), 0, 0, true);
     else
       HideOverlay();
@@ -330,7 +330,8 @@ bool InstantController::Update(const AutocompleteMatch& match,
 
   // If we have an |instant_tab_| use it, else ensure we have an overlay that is
   // current or is using the local overlay.
-  if (!instant_tab_ && !(overlay_ && overlay_->IsUsingLocalOverlay()) &&
+  if (!UseInstantTabToShowSuggestions() &&
+      !(overlay_ && overlay_->IsLocalOverlay()) &&
       !EnsureOverlayIsCurrent(false)) {
     HideOverlay();
     return false;
@@ -341,7 +342,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
       if (!user_input_in_progress) {
         // If the user isn't typing and the omnibox popup is closed, it means a
         // regular navigation, tab-switch or the user hitting Escape.
-        if (instant_tab_) {
+        if (UseInstantTabToShowSuggestions()) {
           // The user is on a search results page. It may be showing results for
           // a partial query the user typed before they hit Escape. Send the
           // omnibox text to the page to restore the original results.
@@ -365,7 +366,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
         last_omnibox_text_.clear();
         last_user_text_.clear();
         last_suggestion_ = InstantSuggestion();
-        if (instant_tab_) {
+        if (UseInstantTabToShowSuggestions()) {
           // On a search results page, tell it to clear old results.
           instant_tab_->Update(string16(), 0, 0, true);
         } else if (search_mode_.is_origin_ntp()) {
@@ -395,7 +396,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
       last_omnibox_text_.clear();
       last_user_text_.clear();
       last_suggestion_ = InstantSuggestion();
-      if (instant_tab_)
+      if (UseInstantTabToShowSuggestions())
         instant_tab_->Update(string16(), 0, 0, true);
       else if (search_mode_.is_origin_ntp())
         overlay_->Update(string16(), 0, 0, true);
@@ -450,7 +451,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
   if (!extended_enabled_)
     search_mode_.mode = SearchMode::MODE_SEARCH_SUGGESTIONS;
 
-  if (instant_tab_) {
+  if (UseInstantTabToShowSuggestions()) {
     // If we have an |instant_tab_| but it doesn't support Instant yet, sever
     // the connection to it so we use the overlay instead. This ensures that the
     // user interaction will be responsive and handles cases where
@@ -461,7 +462,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
       instant_tab_.reset();
   }
 
-  if (!instant_tab_) {
+  if (!UseInstantTabToShowSuggestions()) {
     if (first_interaction_time_.is_null())
       first_interaction_time_ = base::Time::Now();
     allow_overlay_to_show_search_suggestions_ = true;
@@ -469,7 +470,7 @@ bool InstantController::Update(const AutocompleteMatch& match,
     // For extended mode, if the loader is not ready at this point, switch over
     // to a backup loader.
     if (extended_enabled_ && !overlay_->supports_instant() &&
-        !overlay_->IsUsingLocalOverlay() && browser_->GetActiveWebContents()) {
+        !overlay_->IsLocalOverlay() && browser_->GetActiveWebContents()) {
       CreateOverlay(chrome::kChromeSearchLocalOmniboxPopupURL,
                     browser_->GetActiveWebContents());
     }
@@ -491,25 +492,20 @@ bool InstantController::Update(const AutocompleteMatch& match,
 }
 
 scoped_ptr<content::WebContents> InstantController::ReleaseNTPContents() {
-  if (!extended_enabled_)
+  if (!extended_enabled_ || use_local_overlay_only_)
     return scoped_ptr<content::WebContents>(NULL);
 
   LOG_INSTANT_DEBUG_EVENT(this, "ReleaseNTPContents");
 
-  // Don't use the Instant NTP if it doesn't match the current Instant URL.
-  std::string instant_url;
-  if (!GetInstantURL(browser_->profile(), false, &instant_url) ||
-      (ntp_ &&
-       !MatchesOriginAndPath(GURL(ntp_->instant_url()), GURL(instant_url)))) {
-    ntp_.reset();
-  }
+  if (ShouldSwitchToLocalNTP())
+    ResetNTP(false, true);
 
   scoped_ptr<content::WebContents> ntp_contents;
   if (ntp_)
     ntp_contents = ntp_->ReleaseContents();
 
   // Override the blacklist on an explicit user action.
-  ResetNTP(true);
+  ResetNTP(true, false);
   return ntp_contents.Pass();
 }
 
@@ -568,7 +564,7 @@ void InstantController::HandleAutocompleteResults(
     // Unless we are talking to the local overlay, skip SearchProvider, since
     // it only echoes suggestions.
     if (from_search_provider &&
-        (instant_tab_ || !overlay_->IsUsingLocalOverlay()))
+        (UseInstantTabToShowSuggestions() || !overlay_->IsLocalOverlay()))
       continue;
     // Only send autocomplete results when all the providers are done. Skip
     // this check for the SearchProvider, since it isn't done until the page
@@ -600,7 +596,7 @@ void InstantController::HandleAutocompleteResults(
       "HandleAutocompleteResults: total_results=%d",
       static_cast<int>(results.size())));
 
-  if (instant_tab_)
+  if (UseInstantTabToShowSuggestions())
     instant_tab_->SendAutocompleteResults(results);
   else
     overlay_->SendAutocompleteResults(results);
@@ -613,7 +609,7 @@ bool InstantController::OnUpOrDownKeyPressed(int count) {
   if (!instant_tab_ && !overlay_)
     return false;
 
-  if (instant_tab_)
+  if (UseInstantTabToShowSuggestions())
     instant_tab_->UpOrDownKeyPressed(count);
   else
     overlay_->UpOrDownKeyPressed(count);
@@ -638,7 +634,7 @@ void InstantController::OnCancel(const AutocompleteMatch& match,
   last_user_text_ = user_text;
   last_suggestion_ = InstantSuggestion();
 
-  if (instant_tab_)
+  if (UseInstantTabToShowSuggestions())
     instant_tab_->CancelSelection(full_text);
   else
     overlay_->CancelSelection(full_text);
@@ -666,7 +662,7 @@ bool InstantController::CommitIfPossible(InstantCommitType type) {
 
   // If we are on an already committed search results page, send a submit event
   // to the page, but otherwise, nothing else to do.
-  if (instant_tab_) {
+  if (UseInstantTabToShowSuggestions()) {
     if (type == INSTANT_COMMIT_PRESSED_ENTER &&
         (last_match_was_search_ ||
          last_suggestion_.behavior == INSTANT_COMPLETE_NEVER)) {
@@ -695,7 +691,7 @@ bool InstantController::CommitIfPossible(InstantCommitType type) {
     return false;
 
   // Never commit the local overlay.
-  if (overlay_->IsUsingLocalOverlay())
+  if (overlay_->IsLocalOverlay())
     return false;
 
   if (type == INSTANT_COMMIT_FOCUS_LOST) {
@@ -892,7 +888,7 @@ void InstantController::SetInstantEnabled(bool instant_enabled,
   if (extended_enabled_ || instant_enabled_)
     EnsureOverlayIsCurrent(false);
   if (extended_enabled_)
-    ResetNTP(false);
+    ResetNTP(false, false);
   if (instant_tab_)
     instant_tab_->SetDisplayInstantResults(instant_enabled_);
 }
@@ -924,7 +920,7 @@ void InstantController::FocusedOverlayContents() {
 
 void InstantController::ReloadOverlayIfStale() {
   // The local overlay is never stale.
-  if (overlay_ && overlay_->IsUsingLocalOverlay())
+  if (overlay_ && overlay_->IsLocalOverlay())
     return;
 
   // If the overlay is showing or the omnibox has focus, don't delete the
@@ -1114,7 +1110,8 @@ void InstantController::SetSuggestions(
   // Ignore if the message is from an unexpected source.
   if (IsContentsFrom(ntp(), contents))
     return;
-  if (instant_tab_ && !IsContentsFrom(instant_tab(), contents))
+  if (UseInstantTabToShowSuggestions() &&
+      !IsContentsFrom(instant_tab(), contents))
     return;
   if (IsContentsFrom(overlay(), contents) &&
       !allow_overlay_to_show_search_suggestions_)
@@ -1124,22 +1121,11 @@ void InstantController::SetSuggestions(
   if (!suggestions.empty())
     suggestion = suggestions[0];
 
-  if (instant_tab_ &&
-      (search_mode_.is_search_results() || search_mode_.is_ntp()) &&
-      suggestion.behavior == INSTANT_COMPLETE_REPLACE) {
-    // Update |last_omnibox_text_| so that the controller commits the proper
-    // query if the user focuses the omnibox and presses Enter.
-    last_omnibox_text_ = suggestion.text;
-    last_suggestion_ = InstantSuggestion();
-    last_match_was_search_ = suggestion.type == INSTANT_SUGGESTION_SEARCH;
-    // This means a committed page in state search called setValue(). We should
-    // update the omnibox to reflect what the search page says.
-    browser_->SetInstantSuggestion(suggestion);
-    return;
-  }
-
-  // Ignore if we are not currently accepting search suggestions.
-  if (!search_mode_.is_search_suggestions() || last_omnibox_text_.empty())
+  bool can_use_instant_tab = UseInstantTabToShowSuggestions() &&
+      !search_mode_.is_default();
+  bool can_use_overlay = search_mode_.is_search_suggestions() &&
+      !last_omnibox_text_.empty();
+  if (!can_use_instant_tab && !can_use_overlay)
     return;
 
   if (suggestion.behavior == INSTANT_COMPLETE_REPLACE) {
@@ -1243,7 +1229,7 @@ void InstantController::OmniboxLostFocus(gfx::NativeView view_gaining_focus) {
   if (model_.mode().is_default()) {
     // Correct search terms if the user clicked on the committed results page
     // while showing an autocomplete suggestion
-    if (instant_tab_ && !last_suggestion_.text.empty() &&
+    if (UseInstantTabToShowSuggestions() && !last_suggestion_.text.empty() &&
         last_suggestion_.behavior == INSTANT_COMPLETE_NEVER &&
         IsViewInContents(GetViewGainingFocus(view_gaining_focus),
                          instant_tab_->contents())) {
@@ -1279,18 +1265,16 @@ void InstantController::OmniboxLostFocus(gfx::NativeView view_gaining_focus) {
 #endif
 }
 
-void InstantController::ResetNTP(bool ignore_blacklist) {
+void InstantController::ResetNTP(bool ignore_blacklist, bool use_local_ntp) {
   ntp_.reset();
   std::string instant_url;
-  if (browser_->profile()->IsOffTheRecord() ||
-      !GetInstantURL(browser_->profile(), ignore_blacklist, &instant_url)) {
-    // TODO(sreeram|samarth): use local ntp here once available.
-    return;
-  }
+  if (use_local_ntp ||
+      !GetInstantURL(browser_->profile(), ignore_blacklist, &instant_url))
+    instant_url = chrome::kChromeSearchLocalNtpUrl;
   ntp_.reset(new InstantNTP(this, instant_url));
   ntp_->InitContents(browser_->profile(), browser_->GetActiveWebContents(),
                      base::Bind(&InstantController::ResetNTP,
-                                base::Unretained(this), false));
+                                base::Unretained(this), false, false));
 }
 
 bool InstantController::EnsureOverlayIsCurrent(bool ignore_blacklist) {
@@ -1386,7 +1370,7 @@ void InstantController::HideInternal() {
 
 void InstantController::ShowOverlay(int height, InstantSizeUnits units) {
   // If we are on a committed search results page, the |overlay_| is not in use.
-  if (instant_tab_)
+  if (UseInstantTabToShowSuggestions())
     return;
 
   LOG_INSTANT_DEBUG_EVENT(this, base::StringPrintf(
@@ -1415,7 +1399,7 @@ void InstantController::ShowOverlay(int height, InstantSizeUnits units) {
   // - Instant is disabled. The page needs to be able to show only a dropdown.
   // - The page is over a website other than search or an NTP, and is not
   //   already showing at 100% height.
-  if (overlay_->IsUsingLocalOverlay() || !instant_enabled_ ||
+  if (overlay_->IsLocalOverlay() || !instant_enabled_ ||
       (search_mode_.is_origin_default() && !IsFullHeight(model_)))
     model_.SetOverlayState(search_mode_, height, units);
   else
@@ -1493,7 +1477,7 @@ void InstantController::BlacklistAndResetNTP() {
   RecordEventHistogram(INSTANT_CONTROLLER_EVENT_URL_ADDED_TO_BLACKLIST);
   delete ntp_->ReleaseContents().release();
   MessageLoop::current()->DeleteSoon(FROM_HERE, ntp_.release());
-  ResetNTP(false);
+  ResetNTP(false, false);
 }
 
 void InstantController::BlacklistAndResetOverlay() {
@@ -1630,3 +1614,28 @@ bool InstantController::FixSuggestion(InstantSuggestion* suggestion) const {
 
   return false;
 }
+
+bool InstantController::UseInstantTabToShowSuggestions() const {
+  return instant_tab_ && !instant_tab_->IsLocalNTP();
+}
+
+bool InstantController::ShouldSwitchToLocalNTP() const {
+  // If there is no NTP, or no Instant URL or the NTP is stale, switch.
+  std::string instant_url;
+  if (!ntp_ || !GetInstantURL(browser_->profile(), false, &instant_url) ||
+      !MatchesOriginAndPath(GURL(ntp_->instant_url()), GURL(instant_url))) {
+    return true;
+  }
+
+  if (ntp_->supports_instant())
+    return false;
+
+  // If this is not window startup, switch.
+  // TODO(shishir): This is not completely reliable. Find a better way to detect
+  // startup time.
+  if (browser_->GetActiveWebContents())
+    return true;
+
+  return chrome::IsAggressiveLocalNTPFallbackEnabled();
+}
+
diff --git a/chrome/browser/ui/search/instant_controller.h b/chrome/browser/ui/search/instant_controller.h
index b2ca248..ecd333e 100644
--- a/chrome/browser/ui/search/instant_controller.h
+++ b/chrome/browser/ui/search/instant_controller.h
@@ -272,14 +272,15 @@ class InstantController : public InstantPage::Delegate,
   void OmniboxLostFocus(gfx::NativeView view_gaining_focus);
 
   // Creates a new NTP, using the instant_url property of the default
-  // TemplateURL.
-  void ResetNTP(bool ignore_blacklist);
+  // TemplateURL, or chrome::kChromeSearchLocalNTPURL if |use_local_ntp| is
+  // true. For |ignore_blacklist| look at comments in GetInstantURL().
+  void ResetNTP(bool ignore_blacklist, bool use_local_ntp);
 
   // Ensures that |overlay_| uses the Instant URL returned by GetInstantURL(),
   // creating a new overlay if necessary. In extended mode, will fallback to
   // using the kLocalOmniboxPopupURL as the Instant URL in case GetInstantURL()
   // returns false. Returns true if an Instant URL could be determined.
-  // For |ignore_blacklist| look at comments in |GetInstantURL|.
+  // For |ignore_blacklist| look at comments in GetInstantURL().
   bool EnsureOverlayIsCurrent(bool ignore_blacklist);
 
   // Recreates the |overlay_| with |instant_url|. Note that |overlay_| is
@@ -362,6 +363,15 @@ class InstantController : public InstantPage::Delegate,
   // returns false.)
   bool FixSuggestion(InstantSuggestion* suggestion) const;
 
+  // Returns true if we should use |instant_tab_| instead of |overlay_| for
+  // handling suggestions.
+  // TODO(samarth|sreeram): this is brittle. Instead, we should probably just
+  // combine the two local pages into one.
+  bool UseInstantTabToShowSuggestions() const;
+
+  // Returns true if we should switch to using the local NTP.
+  bool ShouldSwitchToLocalNTP() const;
+
   BrowserInstantController* const browser_;
 
   // Whether the extended API and regular API are enabled. If both are false,
diff --git a/chrome/browser/ui/search/instant_overlay.cc b/chrome/browser/ui/search/instant_overlay.cc
index 352bfbc..fa22139 100644
--- a/chrome/browser/ui/search/instant_overlay.cc
+++ b/chrome/browser/ui/search/instant_overlay.cc
@@ -72,10 +72,6 @@ void InstantOverlay::DidNavigate(
   last_navigation_ = add_page_args;
 }
 
-bool InstantOverlay::IsUsingLocalOverlay() const {
-  return instant_url_ == chrome::kChromeSearchLocalOmniboxPopupURL;
-}
-
 void InstantOverlay::Update(const string16& text,
                             size_t selection_start,
                             size_t selection_end,
diff --git a/chrome/browser/ui/search/instant_overlay.h b/chrome/browser/ui/search/instant_overlay.h
index f20a986..5894f80 100644
--- a/chrome/browser/ui/search/instant_overlay.h
+++ b/chrome/browser/ui/search/instant_overlay.h
@@ -67,10 +67,6 @@ class InstantOverlay : public InstantPage,
   // to the history service had this WebContents not been used for Instant.
   void DidNavigate(const history::HistoryAddPageArgs& add_page_args);
 
-  // Returns true if the overlay is using
-  // InstantController::kLocalOmniboxPopupURL as the |instant_url_|.
-  bool IsUsingLocalOverlay() const;
-
   // Overridden from InstantPage:
   virtual void Update(const string16& text,
                       size_t selection_start,
diff --git a/chrome/browser/ui/search/instant_page.cc b/chrome/browser/ui/search/instant_page.cc
index 764a565..8c12ae7 100644
--- a/chrome/browser/ui/search/instant_page.cc
+++ b/chrome/browser/ui/search/instant_page.cc
@@ -6,6 +6,7 @@
 
 #include "base/utf_string_conversions.h"
 #include "chrome/common/render_messages.h"
+#include "chrome/common/url_constants.h"
 #include "content/public/browser/web_contents.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/font.h"
@@ -16,6 +17,16 @@ InstantPage::Delegate::~Delegate() {
 InstantPage::~InstantPage() {
 }
 
+bool InstantPage::IsLocalNTP() const {
+  return contents() &&
+      contents()->GetURL() == GURL(chrome::kChromeSearchLocalNtpUrl);
+}
+
+bool InstantPage::IsLocalOverlay() const {
+  return contents() &&
+      contents()->GetURL() == GURL(chrome::kChromeSearchLocalOmniboxPopupURL);
+}
+
 void InstantPage::Update(const string16& text,
                          size_t selection_start,
                          size_t selection_end,
diff --git a/chrome/browser/ui/search/instant_page.h b/chrome/browser/ui/search/instant_page.h
index 6564945..caaf8d2 100644
--- a/chrome/browser/ui/search/instant_page.h
+++ b/chrome/browser/ui/search/instant_page.h
@@ -114,6 +114,14 @@ class InstantPage : public content::WebContentsObserver {
   // support suddenly).
   bool supports_instant() const { return supports_instant_; }
 
+  // Returns true if the page is the local NTP (i.e. its URL is
+  // chrome::kChromeSearchLocalNTPURL).
+  bool IsLocalNTP() const;
+
+  // Returns true if the page is the local overlay (i.e. its URL is
+  // chrome::kChromeSearchLocalOmniboxPopupURL).
+  bool IsLocalOverlay() const;
+
   // Tells the page that the user typed |text| into the omnibox. If |verbatim|
   // is false, the page predicts the query the user means to type and fetches
   // results for the prediction. If |verbatim| is true, |text| is taken as the