Fix the problem that black background window might occasionally appear in front on Windows

When a new panel is added to a stack, the following things occur:
1) The panel is initially created as always on top on Windows.
2) The panel is changed to non-always-on-top.
3) The background stack window is made to the owner of the new panel window.
4) The background stack window is set to behind the new panel window in z-order.

Occasionally, step 2 might be run after step 4. When this occurs, after step 1, 3 and 4, the background stack window will automatically obtain the always-on-top state since the panel window behind which is set to is always-on-top. For most of time, running step 2 after 4 will remove the always-on-top state for both new panel window and background stack window. However, if chrome is not foreground application, Windows system might fail to deprive the always-on-top state for the background stack window.

The fix is to create the panel window with always-on-top state depending on its collection.

BUG=241224
TEST=Manual test by following the bug report

Review URL: https://chromiumcodereview.appspot.com/14956006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200788 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 26 insertions, 8 deletions

diff --git a/chrome/browser/ui/panels/detached_panel_collection.cc b/chrome/browser/ui/panels/detached_panel_collection.cc
index 3437237..d525dac 100644
--- a/chrome/browser/ui/panels/detached_panel_collection.cc
+++ b/chrome/browser/ui/panels/detached_panel_collection.cc
@@ -190,6 +190,10 @@ bool DetachedPanelCollection::IsPanelMinimized(const Panel* panel) const {
   return false;
 }
 
+bool DetachedPanelCollection::UsesAlwaysOnTopPanels() const {
+  return false;
+}
+
 void DetachedPanelCollection::SavePanelPlacement(Panel* panel) {
   DCHECK(!saved_panel_placement_.panel);
   saved_panel_placement_.panel = panel;
@@ -234,7 +238,6 @@ void DetachedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
   panel->set_attention_mode(
       static_cast<Panel::AttentionMode>(Panel::USE_PANEL_ATTENTION |
                                         Panel::USE_SYSTEM_ATTENTION));
-  panel->SetAlwaysOnTop(false);
   panel->ShowShadow(true);
   panel->EnableResizeByMouse(true);
   panel->UpdateMinimizeRestoreButtonVisibility();
diff --git a/chrome/browser/ui/panels/detached_panel_collection.h b/chrome/browser/ui/panels/detached_panel_collection.h
index 2720bfe..21aeeac 100644
--- a/chrome/browser/ui/panels/detached_panel_collection.h
+++ b/chrome/browser/ui/panels/detached_panel_collection.h
@@ -50,6 +50,7 @@ class DetachedPanelCollection : public PanelCollection {
   virtual bool CanShowMinimizeButton(const Panel* panel) const OVERRIDE;
   virtual bool CanShowRestoreButton(const Panel* panel) const OVERRIDE;
   virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
+  virtual bool UsesAlwaysOnTopPanels() const OVERRIDE;
   virtual void SavePanelPlacement(Panel* panel) OVERRIDE;
   virtual void RestorePanelToSavedPlacement() OVERRIDE;
   virtual void DiscardSavedPanelPlacement() OVERRIDE;
diff --git a/chrome/browser/ui/panels/docked_panel_collection.cc b/chrome/browser/ui/panels/docked_panel_collection.cc
index f17549f..e688b0c 100644
--- a/chrome/browser/ui/panels/docked_panel_collection.cc
+++ b/chrome/browser/ui/panels/docked_panel_collection.cc
@@ -421,6 +421,10 @@ bool DockedPanelCollection::IsPanelMinimized(const Panel* panel) const {
   return panel->expansion_state() != Panel::EXPANDED;
 }
 
+bool DockedPanelCollection::UsesAlwaysOnTopPanels() const {
+  return true;
+}
+
 void DockedPanelCollection::UpdateMinimizedPanelCount() {
   int prev_minimized_panel_count = minimized_panel_count_;
   minimized_panel_count_ = 0;
@@ -760,7 +764,6 @@ void DockedPanelCollection::CloseAll() {
 
 void DockedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
   panel->set_attention_mode(Panel::USE_PANEL_ATTENTION);
-  panel->SetAlwaysOnTop(true);
   panel->ShowShadow(true);
   panel->EnableResizeByMouse(true);
   panel->UpdateMinimizeRestoreButtonVisibility();
diff --git a/chrome/browser/ui/panels/docked_panel_collection.h b/chrome/browser/ui/panels/docked_panel_collection.h
index ccf12ea8..799176d 100644
--- a/chrome/browser/ui/panels/docked_panel_collection.h
+++ b/chrome/browser/ui/panels/docked_panel_collection.h
@@ -64,6 +64,7 @@ class DockedPanelCollection :
   virtual bool CanShowMinimizeButton(const Panel* panel) const OVERRIDE;
   virtual bool CanShowRestoreButton(const Panel* panel) const OVERRIDE;
   virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
+  virtual bool UsesAlwaysOnTopPanels() const OVERRIDE;
   virtual void SavePanelPlacement(Panel* panel) OVERRIDE;
   virtual void RestorePanelToSavedPlacement() OVERRIDE;
   virtual void DiscardSavedPanelPlacement() OVERRIDE;
diff --git a/chrome/browser/ui/panels/panel.cc b/chrome/browser/ui/panels/panel.cc
index 02af37e..d003bbb 100644
--- a/chrome/browser/ui/panels/panel.cc
+++ b/chrome/browser/ui/panels/panel.cc
@@ -498,14 +498,16 @@ panel::Resizability Panel::CanResizeByMouse() const {
   return collection_->GetPanelResizability(this);
 }
 
-void Panel::Initialize(const GURL& url, const gfx::Rect& bounds) {
+void Panel::Initialize(const GURL& url,
+                       const gfx::Rect& bounds,
+                       bool always_on_top) {
   DCHECK(!initialized_);
   DCHECK(!collection_);  // Cannot be added to a collection until fully created.
   DCHECK_EQ(EXPANDED, expansion_state_);
   DCHECK(!bounds.IsEmpty());
   initialized_ = true;
   full_size_ = bounds.size();
-  native_panel_ = CreateNativePanel(this, bounds);
+  native_panel_ = CreateNativePanel(this, bounds, always_on_top);
 
   extension_window_controller_.reset(
       new panel_internal::PanelExtensionWindowController(this, profile_));
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index 1542aa9..deda724 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -146,7 +146,8 @@ class Panel : public BaseWindow,
 
   // Construct a native panel implementation.
   static NativePanel* CreateNativePanel(Panel* panel,
-                                        const gfx::Rect& bounds);
+                                        const gfx::Rect& bounds,
+                                        bool always_on_top);
 
   NativePanel* native_panel() const { return native_panel_; }
 
@@ -199,7 +200,7 @@ class Panel : public BaseWindow,
   // Panel must be initialized to be "fully created" and ready for use.
   // Only called by PanelManager.
   bool initialized() const { return initialized_; }
-  void Initialize(const GURL& url, const gfx::Rect& bounds);
+  void Initialize(const GURL& url, const gfx::Rect& bounds, bool always_on_top);
 
   // This is different from BaseWindow::SetBounds():
   // * SetPanelBounds() is only called by PanelManager to manage its position.
diff --git a/chrome/browser/ui/panels/panel_collection.h b/chrome/browser/ui/panels/panel_collection.h
index 6bc4064..dc53348 100644
--- a/chrome/browser/ui/panels/panel_collection.h
+++ b/chrome/browser/ui/panels/panel_collection.h
@@ -128,6 +128,8 @@ class PanelCollection {
 
   virtual bool IsPanelMinimized(const Panel* panel) const = 0;
 
+  virtual bool UsesAlwaysOnTopPanels() const = 0;
+
   // Saves/restores/discards the placement information of |panel|. This is
   // useful in bringing back the dragging panel to its original positioning
   // when the drag is cancelled. After the placement information is saved,
diff --git a/chrome/browser/ui/panels/panel_manager.cc b/chrome/browser/ui/panels/panel_manager.cc
index ab68a56..ef1b1f9 100644
--- a/chrome/browser/ui/panels/panel_manager.cc
+++ b/chrome/browser/ui/panels/panel_manager.cc
@@ -270,7 +270,7 @@ Panel* PanelManager::CreatePanel(const std::string& app_name,
       adjusted_requested_bounds);
   bounds.AdjustToFit(work_area);
 
-  panel->Initialize(url, bounds);
+  panel->Initialize(url, bounds, collection->UsesAlwaysOnTopPanels());
 
   // Auto resizable feature is enabled only if no initial size is requested.
   if (auto_sizing_enabled() && requested_bounds.width() == 0 &&
@@ -488,6 +488,7 @@ void PanelManager::MovePanelToCollection(
 
   target_collection->AddPanel(panel, positioning_mask);
   target_collection->UpdatePanelOnCollectionChange(panel);
+  panel->SetAlwaysOnTop(target_collection->UsesAlwaysOnTopPanels());
 }
 
 bool PanelManager::ShouldBringUpTitlebars(int mouse_x, int mouse_y) const {
diff --git a/chrome/browser/ui/panels/stacked_panel_collection.cc b/chrome/browser/ui/panels/stacked_panel_collection.cc
index 7e1cc83..6286e37 100644
--- a/chrome/browser/ui/panels/stacked_panel_collection.cc
+++ b/chrome/browser/ui/panels/stacked_panel_collection.cc
@@ -472,6 +472,10 @@ bool StackedPanelCollection::IsPanelMinimized(const Panel* panel) const {
   return panel->expansion_state() != Panel::EXPANDED;
 }
 
+bool StackedPanelCollection::UsesAlwaysOnTopPanels() const {
+  return false;
+}
+
 void StackedPanelCollection::SavePanelPlacement(Panel* panel) {
   DCHECK(!saved_panel_placement_.panel);
   saved_panel_placement_.panel = panel;
@@ -614,7 +618,6 @@ void StackedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
   panel->set_attention_mode(
       static_cast<Panel::AttentionMode>(Panel::USE_PANEL_ATTENTION |
                                         Panel::USE_SYSTEM_ATTENTION));
-  panel->SetAlwaysOnTop(false);
   panel->ShowShadow(false);
   panel->EnableResizeByMouse(true);
   panel->UpdateMinimizeRestoreButtonVisibility();
diff --git a/chrome/browser/ui/panels/stacked_panel_collection.h b/chrome/browser/ui/panels/stacked_panel_collection.h
index 2c95cab..a8219cd 100644
--- a/chrome/browser/ui/panels/stacked_panel_collection.h
+++ b/chrome/browser/ui/panels/stacked_panel_collection.h
@@ -53,6 +53,7 @@ class StackedPanelCollection : public PanelCollection,
   virtual bool CanShowMinimizeButton(const Panel* panel) const OVERRIDE;
   virtual bool CanShowRestoreButton(const Panel* panel) const OVERRIDE;
   virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
+  virtual bool UsesAlwaysOnTopPanels() const OVERRIDE;
   virtual void SavePanelPlacement(Panel* panel) OVERRIDE;
   virtual void RestorePanelToSavedPlacement() OVERRIDE;
   virtual void DiscardSavedPanelPlacement()  OVERRIDE;