[omnibox] Basic implementation of on-clobber ZeroSuggest for Desktop

This CL is the most basic implementation possible of requesting
zero-prefix suggestions (ZeroSuggestProvider) when the user deletes the
permanent text in the omnibox.

In other words, when the flag is on, and the user enters
user_input_in_progress mode by deleting everything, this will request
ZeroSuggestions.

This doesn't implement the oft=2 mode yet, so there's no distinction
between on-clobber and on-focus requests.

Bug: 1106096
Change-Id: I2f0f3353605f82b378cc2d73499b8f03ceb83f32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2335509Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794691}

chrome/browser/ui/views/omnibox/omnibox_view_views.cc

@@ -600,7 +600,7 @@ void OmniboxViewViews::SetFocus(bool is_user_initiated) {
 
   // |is_user_initiated| is true for focus events from keyboard accelerators.
   if (is_user_initiated)
-    model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+    model()->StartZeroSuggestRequest();
 
   // Restore caret visibility if focus is explicitly requested. This is
   // necessary because if we already have invisible focus, the RequestFocus()
@@ -1364,7 +1364,7 @@ bool OmniboxViewViews::OnMousePressed(const ui::MouseEvent& event) {
   //  - The textfield doesn't already have focus.
   //  - Or if the textfield is empty, to cover the NTP ZeroSuggest case.
   if (event.IsOnlyLeftMouseButton() && (!HasFocus() || GetText().empty()))
-    model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+    model()->StartZeroSuggestRequest();
 
   bool handled = views::Textfield::OnMousePressed(event);
 
@@ -1474,7 +1474,7 @@ void OmniboxViewViews::OnGestureEvent(ui::GestureEvent* event) {
   //  - The textfield is taking focus.
   //  - The textfield is focused but empty, to cover the NTP ZeroSuggest case.
   if (gesture_should_take_focus || (HasFocus() && GetText().empty()))
-    model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+    model()->StartZeroSuggestRequest();
 
   views::Textfield::OnGestureEvent(event);
 

components/omnibox/browser/omnibox_edit_model.cc

@@ -42,6 +42,7 @@
 #include "components/omnibox/browser/omnibox_view.h"
 #include "components/omnibox/browser/search_provider.h"
 #include "components/omnibox/browser/suggestion_answer.h"
+#include "components/omnibox/common/omnibox_features.h"
 #include "components/search_engines/template_url.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
 #include "components/search_engines/template_url_service.h"
@@ -467,14 +468,25 @@ bool OmniboxEditModel::ShouldShowCurrentPageIcon() const {
 
 void OmniboxEditModel::UpdateInput(bool has_selected_text,
                                    bool prevent_inline_autocomplete) {
-  bool changed = SetInputInProgressNoNotify(true);
+  bool changed_to_user_input_in_progress = SetInputInProgressNoNotify(true);
   if (!has_focus()) {
-    if (changed)
+    if (changed_to_user_input_in_progress)
       NotifyObserversInputInProgress(true);
     return;
   }
-  StartAutocomplete(has_selected_text, prevent_inline_autocomplete);
-  if (changed)
+
+  if (changed_to_user_input_in_progress && user_text_.empty() &&
+      base::FeatureList::IsEnabled(omnibox::kClobberIsZeroSuggestEntrypoint)) {
+    // In the case the user enters user-input-in-progress mode by clearing
+    // everything (i.e. via Backspace), and the special flag is on, ask for
+    // ZeroSuggestions instead of the normal prefix (as-you-type) autocomplete.
+    StartZeroSuggestRequest(/*user_clobbered_permanent_text=*/true);
+  } else {
+    // Otherwise run the normal prefix (as-you-type) autocomplete.
+    StartAutocomplete(has_selected_text, prevent_inline_autocomplete);
+  }
+
+  if (changed_to_user_input_in_progress)
     NotifyObserversInputInProgress(true);
 }
 
@@ -1072,7 +1084,8 @@ void OmniboxEditModel::OnSetFocus(bool control_down) {
     client_->OnInputStateChanged();
 }
 
-void OmniboxEditModel::ShowOnFocusSuggestionsIfAutocompleteIdle() {
+void OmniboxEditModel::StartZeroSuggestRequest(
+    bool user_clobbered_permanent_text) {
   // Early exit if a query is already in progress or the popup is already open.
   // This is what allows this method to be called multiple times in multiple
   // code locations without harm.
@@ -1084,7 +1097,7 @@ void OmniboxEditModel::ShowOnFocusSuggestionsIfAutocompleteIdle() {
     return;
 
   // Early exit if the user already has a navigation or search query in mind.
-  if (user_input_in_progress_)
+  if (user_input_in_progress_ && !user_clobbered_permanent_text)
     return;
 
   // Send the textfield contents exactly as-is, as otherwise the verbatim
@@ -1093,6 +1106,8 @@ void OmniboxEditModel::ShowOnFocusSuggestionsIfAutocompleteIdle() {
                              client_->GetSchemeClassifier());
   input_.set_current_url(client_->GetURL());
   input_.set_current_title(client_->GetTitle());
+  // TODO(tommycli): Distinguish between on-focus and on-clobber ZeroSuggest
+  // requests.
   input_.set_from_omnibox_focus(true);
   autocomplete_controller()->Start(input_);
 }

components/omnibox/browser/omnibox_edit_model.h

@@ -299,10 +299,11 @@ class OmniboxEditModel {
   // control key is down (at the time we're gaining focus).
   void OnSetFocus(bool control_down);
 
-  // Shows On-Focus Suggestions (ZeroSuggest) if no query is currently running
-  // and the popup is closed. This can be called multiple times without harm,
-  // since it will early-exit if an earlier request is in progress (or done).
-  void ShowOnFocusSuggestionsIfAutocompleteIdle();
+  // Starts a request for zero-prefix suggestions if no query is currently
+  // running and the popup is closed. This can be called multiple times without
+  // harm, since it will early-exit if an earlier request is in progress or
+  // done.
+  void StartZeroSuggestRequest(bool user_clobbered_permanent_text = false);
 
   // Sets the visibility of the caret in the omnibox, if it has focus. The
   // visibility of the caret is reset to visible if either

components/omnibox/browser/omnibox_edit_model_unittest.cc

@@ -270,7 +270,7 @@ TEST_F(OmniboxEditModelTest, RespectUnelisionInZeroSuggest) {
 
   // Test that we don't clobber the unelided text with inline autocomplete text.
   EXPECT_EQ(base::string16(), view()->inline_autocomplete_text());
-  model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+  model()->StartZeroSuggestRequest();
   model()->OnPopupDataChanged(base::string16(), /*is_temporary_text=*/false,
                               base::string16(), base::string16(), false,
                               base::string16());
@@ -290,7 +290,7 @@ TEST_F(OmniboxEditModelTest, RevertZeroSuggestTemporaryText) {
 
   // Simulate getting ZeroSuggestions and arrowing to a different match.
   view()->SelectAll(true);
-  model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+  model()->StartZeroSuggestRequest();
   model()->OnPopupDataChanged(base::ASCIIToUTF16("fake_temporary_text"),
                               /*is_temporary_text=*/true, base::string16(),
                               base::string16(), false, base::string16());

components/omnibox/browser/zero_suggest_provider.cc

@@ -615,10 +615,14 @@ bool ZeroSuggestProvider::AllowZeroSuggestSuggestions(
     return false;
 
   // When the omnibox is empty, only allow zero suggest for the ChromeOS
-  // Launcher and NTP.
+  // Launcher and NTP, unless the clobber flag is on.
+  //
+  // TODO(tommycli): Add more nuance here, likely with an omnibox_focus_type.
   if (input_type == metrics::OmniboxInputType::EMPTY &&
       !(page_class == metrics::OmniboxEventProto::CHROMEOS_APP_LIST ||
-        IsNTPPage(page_class))) {
+        IsNTPPage(page_class) ||
+        base::FeatureList::IsEnabled(
+            omnibox::kClobberIsZeroSuggestEntrypoint))) {
     return false;
   }
 

ios/chrome/browser/ui/omnibox/omnibox_view_ios.mm

@@ -290,7 +290,7 @@ void OmniboxViewIOS::OnDidBeginEditing() {
       model()->set_focus_source(OmniboxFocusSource::OMNIBOX);
     }
 
-    model()->ShowOnFocusSuggestionsIfAutocompleteIdle();
+    model()->StartZeroSuggestRequest();
     model()->OnSetFocus(/*control_down=*/false);
   }