Add Apps.AppListSearchResultDistanceFromOrigin UMA stat.

This CL adds a UMA stat that tracks how far an opened app list search
result is from the top left of the search results view. This will provide
information on the quality of search result ranking.

BUG=485449

Review URL: https://codereview.chromium.org/1132943004

Cr-Commit-Position: refs/heads/master@{#329368}

tools/metrics/histograms/histograms.xml

@@ -533,6 +533,14 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Apps.AppListSearchResultDistanceFromOrigin" units="keystrokes">
+  <owner>calamity@chromium.org</owner>
+  <summary>
+    The minimum number of arrow keys a user would need to press to navigate to
+    the opened search result. This is gathered per click of a search result.
+  </summary>
+</histogram>
+
 <histogram name="Apps.AppListSearchResultOpenDisplayType"
     enum="AppListSearchResultDisplayType">
   <owner>calamity@chromium.org</owner>

ui/app_list/app_list_constants.cc

@@ -132,6 +132,11 @@ const char kSearchResultOpenDisplayTypeHistogram[] =
 // opened.
 const char kSearchQueryLength[] = "Apps.AppListSearchQueryLength";
 
+// The UMA histogram that logs the Manhattan distance from the origin of the
+// search results to the selected result.
+const char kSearchResultDistanceFromOrigin[] =
+    "Apps.AppListSearchResultDistanceFromOrigin";
+
 #if defined(OS_LINUX)
 #if defined(GOOGLE_CHROME_BUILD)
 const char kAppListWMClass[] = "chrome_app_list";

ui/app_list/app_list_constants.h

@@ -83,6 +83,7 @@ APP_LIST_EXPORT extern const ui::ResourceBundle::FontStyle kItemTextFontStyle;
 APP_LIST_EXPORT extern const char kPageOpenedHistogram[];
 APP_LIST_EXPORT extern const char kSearchResultOpenDisplayTypeHistogram[];
 APP_LIST_EXPORT extern const char kSearchQueryLength[];
+APP_LIST_EXPORT extern const char kSearchResultDistanceFromOrigin[];
 
 #if defined(OS_LINUX)
 // The WM_CLASS name for the app launcher window on Linux.

ui/app_list/search_controller.cc

@@ -84,6 +84,11 @@ void SearchController::OpenResult(SearchResult* result, int event_flags) {
 
   UMA_HISTOGRAM_COUNTS_100(kSearchQueryLength, search_box_->text().size());
 
+  if (result->distance_from_origin() >= 0) {
+    UMA_HISTOGRAM_COUNTS_100(kSearchResultDistanceFromOrigin,
+                             result->distance_from_origin());
+  }
+
   result->Open(event_flags);
 
   if (history_ && history_->IsReady()) {

ui/app_list/search_result.cc

@@ -32,6 +32,7 @@ SearchResult::Action::~Action() {}
 SearchResult::SearchResult()
     : relevance_(0),
       display_type_(DISPLAY_LIST),
+      distance_from_origin_(-1),
       voice_result_(false),
       is_installing_(false),
       percent_downloaded_(0) {

ui/app_list/search_result.h

@@ -113,6 +113,11 @@ class APP_LIST_EXPORT SearchResult {
     display_type_ = display_type;
   }
 
+  int distance_from_origin() { return distance_from_origin_; }
+  void set_distance_from_origin(int distance) {
+    distance_from_origin_ = distance;
+  }
+
   const Actions& actions() const {
     return actions_;
   }
@@ -180,6 +185,10 @@ class APP_LIST_EXPORT SearchResult {
   double relevance_;
   DisplayType display_type_;
 
+  // The Manhattan distance from the origin of all search results to this
+  // result. This is logged for UMA.
+  int distance_from_origin_;
+
   Actions actions_;
   bool voice_result_;
 

ui/app_list/views/search_result_container_view.cc

@@ -61,6 +61,10 @@ void SearchResultContainerView::ScheduleUpdate() {
   }
 }
 
+bool SearchResultContainerView::UpdateScheduled() {
+  return update_factory_.HasWeakPtrs();
+}
+
 void SearchResultContainerView::ListItemsAdded(size_t start, size_t count) {
   ScheduleUpdate();
 }
@@ -79,10 +83,10 @@ void SearchResultContainerView::ListItemsChanged(size_t start, size_t count) {
 }
 
 void SearchResultContainerView::DoUpdate() {
+  update_factory_.InvalidateWeakPtrs();
   num_results_ = Update();
   Layout();
   PreferredSizeChanged();
-  update_factory_.InvalidateWeakPtrs();
 }
 
 }  // namespace app_list

ui/app_list/views/search_result_container_view.h

@@ -43,10 +43,22 @@ class APP_LIST_EXPORT SearchResultContainerView : public views::View,
   void set_container_score(double score) { container_score_ = score; }
   double container_score() const { return container_score_; }
 
+  // Updates the distance_from_origin() properties of the results in this
+  // container. |y_index| is the absolute y-index of the first result of this
+  // container (counting from the top of the app list).
+  virtual void NotifyFirstResultYIndex(int y_index) = 0;
+
+  // Gets the number of down keystrokes from the beginning to the end of this
+  // container.
+  virtual int GetYSize() = 0;
+
   // Schedules an Update call using |update_factory_|. Do nothing if there is a
   // pending call.
   void ScheduleUpdate();
 
+  // Returns whether an update is currently scheduled for this container.
+  bool UpdateScheduled();
+
   // Overridden from ui::ListModelObserver:
   void ListItemsAdded(size_t start, size_t count) override;
   void ListItemsRemoved(size_t start, size_t count) override;

ui/app_list/views/search_result_list_view.cc

@@ -144,6 +144,15 @@ void SearchResultListView::OnContainerSelected(bool from_bottom,
   SetSelectedIndex(from_bottom ? num_results() - 1 : 0);
 }
 
+void SearchResultListView::NotifyFirstResultYIndex(int y_index) {
+  for (size_t i = 0; i < static_cast<size_t>(num_results()); ++i)
+    GetResultViewAt(i)->result()->set_distance_from_origin(i + y_index);
+}
+
+int SearchResultListView::GetYSize() {
+  return num_results();
+}
+
 int SearchResultListView::Update() {
   std::vector<SearchResult*> display_results =
       AppListModel::FilterSearchResultsByDisplayType(

ui/app_list/views/search_result_list_view.h

@@ -55,6 +55,8 @@ class APP_LIST_EXPORT SearchResultListView : public gfx::AnimationDelegate,
   // Overridden from SearchResultContainerView:
   void OnContainerSelected(bool from_bottom,
                            bool directional_movement) override;
+  void NotifyFirstResultYIndex(int y_index) override;
+  int GetYSize() override;
 
  private:
   friend class test::SearchResultListViewTest;

ui/app_list/views/search_result_page_view.cc

@@ -157,9 +157,17 @@ void SearchResultPageView::ChildPreferredSizeChanged(views::View* child) {
                 return a->container_score() > b->container_score();
               });
 
+    int result_y_index = 0;
     for (size_t i = 0; i < result_container_views_.size(); ++i) {
-      result_container_views_[i]->ClearSelectedIndex();
-      ReorderChildView(result_container_views_[i]->parent(), i);
+      SearchResultContainerView* view = result_container_views_[i];
+      view->ClearSelectedIndex();
+      ReorderChildView(view->parent(), i);
+
+      // Only notify containers that have finished updating.
+      if (!view->UpdateScheduled())
+        view->NotifyFirstResultYIndex(result_y_index);
+
+      result_y_index += view->GetYSize();
     }
   }
 

ui/app_list/views/search_result_tile_item_list_view.cc

@@ -58,6 +58,15 @@ void SearchResultTileItemListView::OnContainerSelected(
   SetSelectedIndex(select_last ? num_results() - 1 : 0);
 }
 
+void SearchResultTileItemListView::NotifyFirstResultYIndex(int y_index) {
+  for (size_t i = 0; i < static_cast<size_t>(num_results()); ++i)
+    tile_views_[i]->result()->set_distance_from_origin(i + y_index);
+}
+
+int SearchResultTileItemListView::GetYSize() {
+  return num_results() ? 1 : 0;
+}
+
 int SearchResultTileItemListView::Update() {
   std::vector<SearchResult*> display_results =
       AppListModel::FilterSearchResultsByDisplayType(

ui/app_list/views/search_result_tile_item_list_view.h

@@ -30,6 +30,8 @@ class APP_LIST_EXPORT SearchResultTileItemListView
   // Overridden from SearchResultContainerView:
   void OnContainerSelected(bool from_bottom,
                            bool directional_movement) override;
+  void NotifyFirstResultYIndex(int y_index) override;
+  int GetYSize() override;
 
   // Overridden from views::View:
   bool OnKeyPressed(const ui::KeyEvent& event) override;

ui/app_list/views/search_result_tile_item_view.h

@@ -29,6 +29,7 @@ class APP_LIST_EXPORT SearchResultTileItemView
                                     AppListViewDelegate* view_delegate);
   ~SearchResultTileItemView() override;
 
+  SearchResult* result() { return item_; }
   void SetSearchResult(SearchResult* item);
 
   // Overridden from TileItemView:

ui/app_list/views/start_page_view.cc

@@ -126,6 +126,8 @@ class StartPageView::StartPageTilesContainer
   void UpdateSelectedIndex(int old_selected, int new_selected) override;
   void OnContainerSelected(bool from_bottom,
                            bool directional_movement) override;
+  void NotifyFirstResultYIndex(int y_index) override;
+  int GetYSize() override;
 
  private:
   ContentsView* contents_view_;
@@ -218,6 +220,17 @@ void StartPageView::StartPageTilesContainer::UpdateSelectedIndex(
 void StartPageView::StartPageTilesContainer::OnContainerSelected(
     bool /*from_bottom*/,
     bool /*directional_movement*/) {
+  NOTREACHED();
+}
+
+void StartPageView::StartPageTilesContainer::NotifyFirstResultYIndex(
+    int /*y_index*/) {
+  NOTREACHED();
+}
+
+int StartPageView::StartPageTilesContainer::GetYSize() {
+  NOTREACHED();
+  return 0;
 }
 
 ////////////////////////////////////////////////////////////////////////////////