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

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/tabs/tab.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/debug/alias.h"
@@ skipping 405 matching lines @@
       closing_(false),
       dragging_(false),
       detached_(false),
       favicon_hiding_offset_(0),
       loading_animation_frame_(0),
       immersive_loading_step_(0),
       should_display_crashed_favicon_(false),
       animating_media_state_(TAB_MEDIA_STATE_NONE),
       close_button_(NULL),
       title_(new views::Label()),
-      tab_activated_with_last_gesture_begin_(false),
+      tab_activated_with_last_tap_down_(false),
       hover_controller_(this),
       showing_icon_(false),
       showing_media_indicator_(false),
       showing_close_button_(false),
       close_button_color_(0) {
   DCHECK(controller);
   InitTabResources();
 
   // So we get don't get enter/exit on children and don't prematurely stop the
   // hover.
@@ skipping 531 matching lines @@
   hover_controller_.SetLocation(event.location());
   controller_->OnMouseEventInTab(this, event);
 }
 
 void Tab::OnMouseExited(const ui::MouseEvent& event) {
   hover_controller_.Hide();
 }
 
 void Tab::OnGestureEvent(ui::GestureEvent* event) {
   switch (event->type()) {
-    case ui::ET_GESTURE_BEGIN: {
+    case ui::ET_GESTURE_TAP_DOWN: {
       if (event->details().touch_points() != 1)

[tdanderson, 2014/07/24 18:07:21]

This is always true for TAP_DOWN, right?

[tdresser, 2014/07/24 18:17:23]

Yeah, you can safely remove this early-out.

         return;
 
       // See comment in OnMousePressed() as to why we copy the event.
       ui::GestureEvent event_in_parent(*event, static_cast<View*>(this),
                                        parent());
       ui::ListSelectionModel original_selection;
       original_selection.Copy(controller_->GetSelectionModel());
-      tab_activated_with_last_gesture_begin_ = !IsActive();
+      tab_activated_with_last_tap_down_ = !IsActive();
       if (!IsSelected())
         controller_->SelectTab(this);
       gfx::Point loc(event->location());
       views::View::ConvertPointToScreen(this, &loc);
       ui::GestureEvent cloned_event(event_in_parent, parent(),
                                     static_cast<View*>(this));
       controller_->MaybeStartDrag(this, cloned_event, original_selection);
       break;
     }
 
-    case ui::ET_GESTURE_END:
+    case ui::ET_GESTURE_SCROLL_END:
+    case ui::ET_SCROLL_FLING_START:
       controller_->EndDrag(END_DRAG_COMPLETE);
       break;
 
     case ui::ET_GESTURE_SCROLL_UPDATE:

[tdanderson, 2014/07/24 18:07:21]

If this class doesn't handle SCROLL_BEGIN, is it correct for it to be handling
SCROLL_UPDATE and SCROLL_END?

[tdresser, 2014/07/24 18:17:23]

Yeah, that's fine.

[sadrul, 2014/07/24 19:12:13]

Should it handle SCROLL_BEGIN, though?

[tdanderson, 2014/07/25 17:16:10]

I will look into this in more detail when I put up the CL with just the
Tab/TabStrip code.

       controller_->ContinueDrag(this, *event);
       break;
 
     default:
       break;
   }
   event->SetHandled();
 }
 
 void Tab::GetAccessibleState(ui::AXViewState* state) {
@@ skipping 638 matching lines @@
                          const gfx::ImageSkia& image) {
   DCHECK_NE(scale_factor, ui::SCALE_FACTOR_NONE);
   ImageCacheEntry entry;
   entry.resource_id = resource_id;
   entry.scale_factor = scale_factor;
   entry.image = image;
   image_cache_->push_front(entry);
   if (image_cache_->size() > kMaxImageCacheSize)
     image_cache_->pop_back();
 }