[WIP] Allow scroll events to permanently change the default gesture handler in RootView

chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc

Index: chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc
diff --git a/chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc b/chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc
index c7226a6a01346003e2c951da3e9449ddb0e3340e..da2efb70ed2fe9e8b337f03e1da0bb5b3bb6dcf5 100644
--- a/chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc
+++ b/chrome/browser/ui/views/tabs/tab_drag_controller_interactive_uitest.cc
@@ -321,7 +321,9 @@ IN_PROC_BROWSER_TEST_F(TabDragCaptureLostTest, ReleaseCaptureOnDrag) {
   EXPECT_FALSE(tab_strip->IsDragSessionActive());
 }
 
-IN_PROC_BROWSER_TEST_F(TabDragControllerTest, GestureEndShouldEndDragTest) {
+// Tests that a tab dragging session begins and ends at the correct times
+// when dispatching gestures.
+IN_PROC_BROWSER_TEST_F(TabDragControllerTest, DragWithGesture) {
   AddTabAndResetBrowser(browser());
 
   TabStrip* tab_strip = GetTabStripForBrowser(browser());
@@ -329,23 +331,51 @@ IN_PROC_BROWSER_TEST_F(TabDragControllerTest, GestureEndShouldEndDragTest) {
   Tab* tab1 = tab_strip->tab_at(1);
   gfx::Point tab_1_center(tab1->width() / 2, tab1->height() / 2);
 
-  ui::GestureEvent gesture_begin(
+  EXPECT_FALSE(TabDragController::IsActive());
+  EXPECT_FALSE(tab_strip->IsDragSessionActive());
+
+  // A ui::ET_GESTURE_TAP_DOWN dispatched on the tab should set the
+  // drag controller as active and initiate the drag session.
+  ui::GestureEvent gesture_tap_down(
       tab_1_center.x(),
       tab_1_center.x(),
       0,
       base::TimeDelta(),
       ui::GestureEventDetails(ui::ET_GESTURE_BEGIN, 0.0f, 0.0f));
-  tab_strip->MaybeStartDrag(tab1, gesture_begin,
-    tab_strip->GetSelectionModel());
+  tab1->OnGestureEvent(&gesture_tap_down);
+  EXPECT_TRUE(TabDragController::IsActive());
+  EXPECT_TRUE(tab_strip->IsDragSessionActive());
+
+  // We should remain in the drag session if a ui::ET_GESTURE_SCROLL_BEGIN
+  // and a ui::ET_GESTURE_SCROLL_UPDATE are dispatched to the tab strip.
+  ui::GestureEvent gesture_scroll_begin(
+      tab_1_center.x(),
+      tab_1_center.x(),
+      0,
+      base::TimeDelta(),
+      ui::GestureEventDetails(ui::ET_GESTURE_SCROLL_BEGIN, 0.0f, 0.0f));
+  ui::GestureEvent gesture_scroll_update(
+      tab_1_center.x(),
+      tab_1_center.x(),
+      0,
+      base::TimeDelta(),
+      ui::GestureEventDetails(ui::ET_GESTURE_SCROLL_UPDATE, 0.0f, 0.0f));
+  tab_strip->OnGestureEvent(&gesture_scroll_begin);
+  EXPECT_TRUE(TabDragController::IsActive());
+  EXPECT_TRUE(tab_strip->IsDragSessionActive());
+  tab_strip->OnGestureEvent(&gesture_scroll_update);
   EXPECT_TRUE(TabDragController::IsActive());
+  EXPECT_TRUE(tab_strip->IsDragSessionActive());
 
-  ui::GestureEvent gesture_end(
+  // A ui::ET_GESTURE_SCROLL_END dispatched to the tab strip should end the
+  // drag session.
+  ui::GestureEvent gesture_scroll_end(
       tab_1_center.x(),
       tab_1_center.x(),
       0,
       base::TimeDelta(),
-      ui::GestureEventDetails(ui::ET_GESTURE_END, 0.0f, 0.0f));
-  tab_strip->OnGestureEvent(&gesture_end);
+      ui::GestureEventDetails(ui::ET_GESTURE_SCROLL_END, 0.0f, 0.0f));
+  tab_strip->OnGestureEvent(&gesture_scroll_end);
   EXPECT_FALSE(TabDragController::IsActive());
   EXPECT_FALSE(tab_strip->IsDragSessionActive());
 }