Prevent a user from hiding the shelf via a gesture when there are no visible windows

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index 68302878ad26b2618d1f535db572c9167d6702f3..db45c681e8e053282f840bcddb664756867fee18 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -36,6 +36,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "ui/aura/client/activation_client.h"
+#include "ui/aura/client/cursor_client.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/events/event.h"
 #include "ui/base/events/event_handler.h"
@@ -280,7 +281,8 @@ void ShelfLayoutManager::LayoutShelf() {
   if (shelf_->launcher())
     shelf_->launcher()->SetLauncherViewBounds(
         target_bounds.launcher_bounds_in_shelf);
-  GetLayer(shelf_->status_area_widget())->SetOpacity(target_bounds.opacity);
+  GetLayer(shelf_->status_area_widget())->SetOpacity(
+      target_bounds.status_opacity);
   // TODO(harrym): Once status area widget is a child view of shelf
   // this can be simplified.
   gfx::Rect status_bounds = target_bounds.status_bounds_in_shelf;
@@ -571,12 +573,6 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
   state.window_state = workspace_controller_ ?
       workspace_controller_->GetWindowState() : WORKSPACE_WINDOW_STATE_DEFAULT;
 
-  // It's possible for SetState() when a window becomes maximized but the state

[pkotwicz, 2013/08/09 00:04:34]

This comment is outdated. State::window_state now exists

-  // won't have changed value. Do the dimming check before the early exit.
-  shelf_->SetDimsShelf(
-      (state.visibility_state == SHELF_VISIBLE) &&
-      state.window_state == WORKSPACE_WINDOW_STATE_MAXIMIZED);
-
   if (state_.Equals(state))
     return;  // Nothing changed.
 
@@ -631,18 +627,11 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
       old_state.visibility_state != SHELF_VISIBLE) {
     change_type = BackgroundAnimator::CHANGE_IMMEDIATE;
   } else {
-    // Delay updating the background when going from SHELF_AUTO_HIDE_SHOWN to
-    // SHELF_AUTO_HIDE_HIDDEN until the shelf animates out. Otherwise during the
-    // animation you see the background change.
-    // Also delay the animation when the shelf was hidden, and has just been
-    // made visible (e.g. using a gesture-drag).
-    if (state.visibility_state == SHELF_AUTO_HIDE &&

[pkotwicz, 2013/08/09 00:04:34]

To the extent of my understanding this is dead code (and always has been).
ShelfLayoutManager::GetShelfBackgroundType() does not take the auto hide state
into account.

I beleive that the intention of this code is to delay the shelf background
change when in maximized mode and transitioning from a visible shelf to an auto
hidden shelf. (Making that occur is not trivial so I am leaving that bug fix for
another time but am still removing the dead code).

-        state.auto_hide_state == SHELF_AUTO_HIDE_HIDDEN &&
-        old_state.visibility_state == SHELF_AUTO_HIDE) {
-      delay_background_change = true;
-    } else if (state.visibility_state == SHELF_VISIBLE &&
-               old_state.visibility_state == SHELF_AUTO_HIDE &&
-               old_state.auto_hide_state == SHELF_AUTO_HIDE_HIDDEN) {
+    // Delay the animation when the shelf was hidden, and has just been made
+    // visible (e.g. using a gesture-drag).
+    if (state.visibility_state == SHELF_VISIBLE &&
+        old_state.visibility_state == SHELF_AUTO_HIDE &&
+        old_state.auto_hide_state == SHELF_AUTO_HIDE_HIDDEN) {
       delay_background_change = true;
     }
   }
@@ -653,7 +642,14 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
     // UpdateShelfBackground deletes itself when the animation is done.
     update_shelf_observer_ = new UpdateShelfObserver(this);
     status_animation_setter.AddObserver(update_shelf_observer_);
+  } else {

[pkotwicz, 2013/08/09 00:04:34]

Some house cleaning.

+    UpdateShelfBackground(change_type);
   }
+
+  shelf_->SetDimsShelf(
+      (state.visibility_state == SHELF_VISIBLE) &&
+      state.window_state == WORKSPACE_WINDOW_STATE_MAXIMIZED);
+
   ui::Layer* layer = GetLayer(shelf_->status_area_widget());
   // TODO(harrym): Remove when status_area is view (crbug.com/180422).
   gfx::Rect status_bounds = target_bounds.status_bounds_in_shelf;
@@ -666,8 +662,6 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
   Shell::GetInstance()->SetDisplayWorkAreaInsets(
       root_window_, target_bounds.work_area_insets);
   UpdateHitTestBounds();
-  if (!delay_background_change)
-    UpdateShelfBackground(change_type);

[sadrul, 2013/08/09 05:30:13]

This change, the change between newlines 645-652, oldlines 634-645 and 574-579
are not related to fixing this bug, right? This code is sufficiently brittle and
source of a lot of subtle bugs that this kind of clean-up is best done in a
separate CL, even if it looks innocuous.

 
   // OnAutoHideStateChanged Should be emitted when:
   //  - firstly state changed to auto-hide from other state
@@ -789,7 +783,8 @@ void ShelfLayoutManager::CalculateTargetBounds(
        state.visibility_state == SHELF_AUTO_HIDE) ? 1.0f : 0.0f;
   target_bounds->status_opacity =
       (state.visibility_state == SHELF_AUTO_HIDE &&
-       state.auto_hide_state == SHELF_AUTO_HIDE_HIDDEN) ?
+       state.auto_hide_state == SHELF_AUTO_HIDE_HIDDEN &&
+       gesture_drag_status_ != GESTURE_DRAG_IN_PROGRESS) ?
       0.0f : target_bounds->opacity;
 
   if (gesture_drag_status_ == GESTURE_DRAG_IN_PROGRESS)
@@ -941,9 +936,6 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
   if (visibility_state != SHELF_AUTO_HIDE || !shelf_)
     return SHELF_AUTO_HIDE_HIDDEN;
 
-  if (gesture_drag_status_ == GESTURE_DRAG_COMPLETE_IN_PROGRESS)
-    return gesture_drag_auto_hide_state_;
-
   Shell* shell = Shell::GetInstance();
   if (shell->GetAppListTargetVisibility())
     return SHELF_AUTO_HIDE_SHOWN;
@@ -961,10 +953,36 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
   if (shelf_->IsActive() || shelf_->status_area_widget()->IsActive())
     return SHELF_AUTO_HIDE_SHOWN;
 
+  const std::vector<aura::Window*> windows =
+      ash::MruWindowTracker::BuildWindowList(false);
+
+  // Process the window list and check if there are any visible windows.
+  bool visible_window = false;
+  for (size_t i = 0; i < windows.size(); ++i) {
+    if (windows[i] && windows[i]->IsVisible() &&
+        !ash::wm::IsWindowMinimized(windows[i]) &&
+        root_window_ == windows[i]->GetRootWindow()) {
+      visible_window = true;
+      break;
+    }
+  }
+  // If there are no visible windows do not hide the shelf.
+  if (!visible_window)
+    return SHELF_AUTO_HIDE_SHOWN;
+
+  if (gesture_drag_status_ == GESTURE_DRAG_COMPLETE_IN_PROGRESS)
+    return gesture_drag_auto_hide_state_;
+
   // Don't show if the user is dragging the mouse.
   if (auto_hide_event_filter_.get() && auto_hide_event_filter_->in_mouse_drag())
     return SHELF_AUTO_HIDE_HIDDEN;
 
+  // Ignore the mouse position if mouse events are disabled.
+  aura::client::CursorClient* cursor_client = aura::client::GetCursorClient(
+      shelf_->GetNativeWindow()->GetRootWindow());
+  if (!cursor_client->IsMouseEventsEnabled())
+    return SHELF_AUTO_HIDE_HIDDEN;
+
   gfx::Rect shelf_region = shelf_->GetWindowBoundsInScreen();
   if (shelf_->status_area_widget() &&
       shelf_->status_area_widget()->IsMessageBubbleShown() &&
@@ -1005,19 +1023,7 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
     return SHELF_AUTO_HIDE_SHOWN;
   }
 
-  const std::vector<aura::Window*> windows =
-      ash::MruWindowTracker::BuildWindowList(false);
-
-  // Process the window list and check if there are any visible windows.
-  for (size_t i = 0; i < windows.size(); ++i) {
-    if (windows[i] && windows[i]->IsVisible() &&
-        !ash::wm::IsWindowMinimized(windows[i]) &&
-        root_window_ == windows[i]->GetRootWindow())
-      return SHELF_AUTO_HIDE_HIDDEN;
-  }
-
-  // If there are no visible windows do not hide the shelf.
-  return SHELF_AUTO_HIDE_SHOWN;
+  return SHELF_AUTO_HIDE_HIDDEN;
 }
 
 void ShelfLayoutManager::UpdateHitTestBounds() {