Treat up-swipe as a close regardless of container height

When the user doesn't swipe, the container is animated open or closed based on
the final height from dragging upon gesture end. Previously, only down-swipes
were treated specially: swiping down fast enough opened the container regardless
of its height.

This treats swiping up specially too, causing the container to close.

Bug: None
Change-Id: I7555e00dbddb21128175d36a2209139c15cf52d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2128968
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755129}

chrome/browser/ui/views/frame/webui_tab_strip_container_view.cc

@@ -190,7 +190,7 @@ class WebUITabStripContainerView::DragToOpenHandler : public ui::EventHandler {
         break;
       case ui::ET_GESTURE_SCROLL_END:
         if (drag_in_progress_) {
-          container_->EndDragToOpen(false);
+          container_->EndDragToOpen();
           event->SetHandled();
           drag_in_progress_ = false;
         }
@@ -206,7 +206,16 @@ class WebUITabStripContainerView::DragToOpenHandler : public ui::EventHandler {
           // have been sent. Tell the container a drag began.
           container_->UpdateHeightForDragToOpen(0.0f);
         }
-        container_->EndDragToOpen(event->details().swipe_down());
+
+        if (event->details().swipe_down() || event->details().swipe_up()) {
+          container_->EndDragToOpen(event->details().swipe_down()
+                                        ? FlingDirection::kDown
+                                        : FlingDirection::kUp);
+        } else {
+          // Treat a sideways swipe as a normal drag end.
+          container_->EndDragToOpen();
+        }
+
         event->SetHandled();
         drag_in_progress_ = false;
         break;
@@ -215,7 +224,7 @@ class WebUITabStripContainerView::DragToOpenHandler : public ui::EventHandler {
           // If an unsupported gesture is sent, ensure that we still
           // finish the drag on gesture end. Otherwise, the container
           // will be stuck partially open.
-          container_->EndDragToOpen(false);
+          container_->EndDragToOpen();
           event->SetHandled();
           drag_in_progress_ = false;
         }
@@ -423,18 +432,25 @@ void WebUITabStripContainerView::UpdateHeightForDragToOpen(float height_delta) {
   PreferredSizeChanged();
 }
 
-void WebUITabStripContainerView::EndDragToOpen(bool fling_to_open) {
+void WebUITabStripContainerView::EndDragToOpen(
+    base::Optional<FlingDirection> fling_direction) {
   if (!current_drag_height_)
     return;
 
   const int final_drag_height = *current_drag_height_;
   current_drag_height_ = base::nullopt;
 
-  // If we are at least halfway open by now, animate fully open.
-  // Otherwise, animate back to closed.
+  // If this wasn't a fling, determine whether to open or close based on
+  // final height.
   const double open_proportion =
       static_cast<double>(final_drag_height) / desired_height_;
-  const bool opening = fling_to_open || open_proportion >= 0.5;
+  bool opening = open_proportion >= 0.5;
+  if (fling_direction) {
+    // If this was a fling, ignore the final height and use the fling
+    // direction.
+    opening = fling_direction == FlingDirection::kDown;
+  }
+
   if (opening) {
     iph_tracker_->NotifyEvent(feature_engagement::events::kWebUITabStripOpened);
     RecordTabStripUIOpenHistogram(TabStripUIOpenAction::kToolbarDrag);

chrome/browser/ui/views/frame/webui_tab_strip_container_view.h

@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_UI_VIEWS_FRAME_WEBUI_TAB_STRIP_CONTAINER_VIEW_H_
 
 #include <memory>
+#include <set>
 
 #include "base/optional.h"
 #include "base/scoped_observer.h"
@@ -92,10 +93,16 @@ class WebUITabStripContainerView : public TabStripUIEmbedder,
   // Called as we are dragged open.
   void UpdateHeightForDragToOpen(float height_delta);
 
-  // Called when drag-to-open finishes. If |fling_to_open| is true, the
-  // user released their touch with a high enough velocity that we
-  // should animate open regardless of the final height.
-  void EndDragToOpen(bool fling_to_open);
+  enum class FlingDirection {
+    kUp,
+    kDown,
+  };
+
+  // Called when drag-to-open finishes. If |fling_direction| is present,
+  // the user released their touch with a high velocity. We should use
+  // just this direction to animate open or closed.
+  void EndDragToOpen(
+      base::Optional<FlingDirection> fling_direction = base::nullopt);
 
   void SetContainerTargetVisibility(bool target_visible);
 

chrome/browser/ui/views/frame/webui_tab_strip_container_view_unittest.cc

@@ -143,3 +143,5 @@ TEST_F(WebUITabStripDevToolsTest, DevToolsWindowHasNoTabStrip) {
   ui::TouchUiController::TouchUiScoperForTesting reenable_touch_mode(true);
   EXPECT_EQ(nullptr, browser_view()->webui_tab_strip());
 }
+
+// TODO(crbug.com/1066624): add coverage of open and close gestures.