Cleanup to keep panel from manipulating its panel strip assignment directly.

Only PanelManager adds/removes panels from panel strips.
Only exception is in tests.

BUG=None
TEST=Existing tests.


Review URL: http://codereview.chromium.org/9560002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@124806 0039d316-1c4b-4281-b951-d872f2087c98

13 files changed, 216 insertions, 148 deletions

diff --git a/chrome/browser/ui/panels/detached_panel_browsertest.cc b/chrome/browser/ui/panels/detached_panel_browsertest.cc
index b2b5e1b..24e22c1 100644
--- a/chrome/browser/ui/panels/detached_panel_browsertest.cc
+++ b/chrome/browser/ui/panels/detached_panel_browsertest.cc
@@ -12,8 +12,7 @@
 class DetachedPanelBrowserTest : public BasePanelBrowserTest {
 };
 
-IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest,
-                       DISABLED_CheckDetachedPanelProperties) {
+IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest, CheckDetachedPanelProperties) {
   PanelManager* panel_manager = PanelManager::GetInstance();
   DetachedPanelStrip* detached_strip = panel_manager->detached_strip();
 
@@ -27,14 +26,13 @@ IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest,
   // Move panels to detached strip.
   EXPECT_EQ(2, panel_manager->num_panels());
   EXPECT_EQ(0, detached_strip->num_panels());
-  panel1->MoveToStrip(detached_strip);
-  panel2->MoveToStrip(detached_strip);
+  panel_manager->MovePanelToStrip(panel1, PanelStrip::DETACHED);
+  panel_manager->MovePanelToStrip(panel2, PanelStrip::DETACHED);
   EXPECT_EQ(2, panel_manager->num_panels());
   EXPECT_EQ(2, detached_strip->num_panels());
 
-  std::vector<Panel*> panels = panel_manager->panels();
-  EXPECT_EQ(panel1, panels[0]);
-  EXPECT_EQ(panel2, panels[1]);
+  EXPECT_TRUE(detached_strip->HasPanel(panel1));
+  EXPECT_TRUE(detached_strip->HasPanel(panel2));
 
   EXPECT_TRUE(panel1->draggable());
   EXPECT_TRUE(panel2->draggable());
@@ -44,11 +42,10 @@ IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest, DragDetachedPanel) {
   PanelManager* panel_manager = PanelManager::GetInstance();
-  DetachedPanelStrip* detached_strip = panel_manager->detached_strip();
 
   // Create one detached panel.
   Panel* panel = CreatePanelWithBounds("Panel1", gfx::Rect(0, 0, 250, 200));
-  panel->MoveToStrip(detached_strip);
+  panel_manager->MovePanelToStrip(panel, PanelStrip::DETACHED);
 
   // Test that the detached panel can be dragged anywhere.
   scoped_ptr<NativePanelTesting> panel_testing(
@@ -101,10 +98,10 @@ IN_PROC_BROWSER_TEST_F(DetachedPanelBrowserTest, CloseDetachedPanelOnDrag) {
   Panel* panel2 = CreatePanelWithBounds("Panel2", gfx::Rect(0, 0, 110, 110));
   Panel* panel3 = CreatePanelWithBounds("Panel3", gfx::Rect(0, 0, 120, 120));
   Panel* panel4 = CreatePanelWithBounds("Panel4", gfx::Rect(0, 0, 130, 130));
-  panel1->MoveToStrip(detached_strip);
-  panel2->MoveToStrip(detached_strip);
-  panel3->MoveToStrip(detached_strip);
-  panel4->MoveToStrip(detached_strip);
+  panel_manager->MovePanelToStrip(panel1, PanelStrip::DETACHED);
+  panel_manager->MovePanelToStrip(panel2, PanelStrip::DETACHED);
+  panel_manager->MovePanelToStrip(panel3, PanelStrip::DETACHED);
+  panel_manager->MovePanelToStrip(panel4, PanelStrip::DETACHED);
   ASSERT_EQ(4, detached_strip->num_panels());
 
   scoped_ptr<NativePanelTesting> panel1_testing(
diff --git a/chrome/browser/ui/panels/detached_panel_strip.cc b/chrome/browser/ui/panels/detached_panel_strip.cc
index c1c1a78..acc89a8 100644
--- a/chrome/browser/ui/panels/detached_panel_strip.cc
+++ b/chrome/browser/ui/panels/detached_panel_strip.cc
@@ -34,12 +34,15 @@ void DetachedPanelStrip::RefreshLayout() {
 }
 
 void DetachedPanelStrip::AddPanel(Panel* panel) {
-  DCHECK_EQ(this, panel->panel_strip());
+  DCHECK_NE(this, panel->panel_strip());
+  panel->set_panel_strip(this);
   panels_.insert(panel);
 }
 
-bool DetachedPanelStrip::RemovePanel(Panel* panel) {
-  return panels_.erase(panel) != 0;
+void DetachedPanelStrip::RemovePanel(Panel* panel) {
+  DCHECK_EQ(this, panel->panel_strip());
+  panel->set_panel_strip(NULL);
+  panels_.erase(panel);
 }
 
 void DetachedPanelStrip::CloseAll() {
@@ -77,6 +80,12 @@ void DetachedPanelStrip::RestorePanel(Panel* panel) {
   NOTIMPLEMENTED();
 }
 
+bool DetachedPanelStrip::IsPanelMinimized(const Panel* panel) const {
+  DCHECK_EQ(this, panel->panel_strip());
+  NOTIMPLEMENTED();
+  return false;
+}
+
 bool DetachedPanelStrip::CanShowPanelAsActive(const Panel* panel) const {
   // All detached panels can be shown as active.
   return true;
diff --git a/chrome/browser/ui/panels/detached_panel_strip.h b/chrome/browser/ui/panels/detached_panel_strip.h
index 4ea0c4f..0beedf9 100644
--- a/chrome/browser/ui/panels/detached_panel_strip.h
+++ b/chrome/browser/ui/panels/detached_panel_strip.h
@@ -28,7 +28,7 @@ class DetachedPanelStrip : public PanelStrip {
   virtual void SetDisplayArea(const gfx::Rect& display_area) OVERRIDE;
   virtual void RefreshLayout() OVERRIDE;
   virtual void AddPanel(Panel* panel) OVERRIDE;
-  virtual bool RemovePanel(Panel* panel) OVERRIDE;
+  virtual void RemovePanel(Panel* panel) OVERRIDE;
   virtual void CloseAll() OVERRIDE;
   virtual void ResizePanelWindow(
       Panel* panel,
@@ -37,6 +37,7 @@ class DetachedPanelStrip : public PanelStrip {
   virtual void ActivatePanel(Panel* panel) OVERRIDE;
   virtual void MinimizePanel(Panel* panel) OVERRIDE;
   virtual void RestorePanel(Panel* panel) OVERRIDE;
+  virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
   virtual bool CanShowPanelAsActive(const Panel* panel) const OVERRIDE;
   virtual bool CanDragPanel(const Panel* panel) const OVERRIDE;
   virtual void StartDraggingPanel(Panel* panel) OVERRIDE;
diff --git a/chrome/browser/ui/panels/docked_panel_strip.cc b/chrome/browser/ui/panels/docked_panel_strip.cc
index 4fa17f3..57a4bee 100644
--- a/chrome/browser/ui/panels/docked_panel_strip.cc
+++ b/chrome/browser/ui/panels/docked_panel_strip.cc
@@ -11,7 +11,6 @@
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "chrome/browser/ui/browser.h"
-#include "chrome/browser/ui/panels/overflow_panel_strip.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
 #include "chrome/browser/ui/panels/panel_mouse_watcher.h"
 #include "chrome/common/chrome_notification_types.h"
@@ -59,7 +58,6 @@ DockedPanelStrip::DockedPanelStrip(PanelManager* panel_manager)
       panel_manager_(panel_manager),
       minimized_panel_count_(0),
       are_titlebars_up_(false),
-      disable_layout_refresh_(false),
       delayed_titlebar_action_(NO_ACTION),
       titlebar_action_factory_(this) {
   dragging_panel_current_iterator_ = dragging_panel_original_iterator_ =
@@ -86,9 +84,10 @@ void DockedPanelStrip::SetDisplayArea(const gfx::Rect& display_area) {
 }
 
 void DockedPanelStrip::AddPanel(Panel* panel) {
-  DCHECK_EQ(this, panel->panel_strip());
+  DCHECK_NE(this, panel->panel_strip());
+  panel->set_panel_strip(this);
 
-  // Always update limits, even for exiting panels, in case the maximums changed
+  // Always update limits, even on existing panels, in case the limits changed
   // while panel was out of the strip.
   int max_panel_width = GetMaxPanelWidth();
   int max_panel_height = GetMaxPanelHeight();
@@ -100,16 +99,7 @@ void DockedPanelStrip::AddPanel(Panel* panel) {
   int width = restored_size.width();
 
   if (panel->initialized()) {
-    // Bump panels in the strip to make room for this panel.
-    // Prevent layout refresh when panel is removed from this strip.
-    disable_layout_refresh_ = true;
-    PanelStrip* overflow_strip = panel_manager_->overflow_strip();
-    int x;
-    while ((x = GetRightMostAvailablePosition() - width) < display_area_.x()) {
-      DCHECK(!panels_.empty());
-      panels_.back()->MoveToStrip(overflow_strip);
-    }
-    disable_layout_refresh_ = false;
+    int x = FitPanelWithWidth(width);
 
     Panel::ExpansionState expansion_state_to_restore;
     if (panel->expansion_state() == Panel::EXPANDED) {
@@ -124,7 +114,6 @@ void DockedPanelStrip::AddPanel(Panel* panel) {
       }
       IncrementMinimizedPanels();
     }
-
     int y =
         GetBottomPositionForExpansionState(expansion_state_to_restore) - height;
     panel->SetPanelBounds(gfx::Rect(x, y, width, height));
@@ -203,45 +192,43 @@ int DockedPanelStrip::GetRightMostAvailablePosition() const {
       (panels_.back()->GetBounds().x() - kPanelsHorizontalSpacing);
 }
 
-bool DockedPanelStrip::RemovePanel(Panel* panel) {
-  if (panel->has_temporary_layout()) {
-    panels_in_temporary_layout_.erase(panel);
-    return true;
-  }
-
-  Panels::iterator iter = find(panels_.begin(), panels_.end(), panel);
-  if (iter == panels_.end())
-    return false;
+void DockedPanelStrip::RemovePanel(Panel* panel) {
+  DCHECK_EQ(this, panel->panel_strip());
+  panel->set_panel_strip(NULL);
 
   if (panel->expansion_state() != Panel::EXPANDED)
     DecrementMinimizedPanels();
 
-  // Removing an element from the list will invalidate the iterator that refers
-  // to it. So we need to check if the dragging panel iterators are affected.
-  bool update_original_dragging_iterator_after_erase = false;
-  if (dragging_panel_original_iterator_ != panels_.end()) {
-    if (dragging_panel_current_iterator_ == iter) {
-      // If the dragging panel is being removed, set both dragging iterators to
-      // the end of the list.
-      dragging_panel_current_iterator_ = dragging_panel_original_iterator_ =
-          panels_.end();
-    } else if (dragging_panel_original_iterator_ == iter) {
-      // If |dragging_panel_original_iterator_| refers to the element being
-      // removed, set the flag so that the iterator can be updated to next
-      // element.
-      update_original_dragging_iterator_after_erase = true;
-    }
+  if (panel->has_temporary_layout()) {
+    panels_in_temporary_layout_.erase(panel);
+    return;
   }
 
-  iter = panels_.erase(iter);
-
-  if (update_original_dragging_iterator_after_erase)
-    dragging_panel_original_iterator_ = iter;
-
-  if (!disable_layout_refresh_)
+  // Removing an element from the list will invalidate the iterator that refers
+  // to it. We need to update the iterator in that case.
+  DCHECK(dragging_panel_current_iterator_ == panels_.end() ||
+         *dragging_panel_current_iterator_ != panel);
+  bool update_iterator_after_erase =
+      (dragging_panel_original_iterator_ != panels_.end() &&
+       *dragging_panel_original_iterator_ == panel);
+
+  // Optimize for the common case of removing the last panel.
+  DCHECK(!panels_.empty());
+  if (panels_.back() == panel) {
+    panels_.pop_back();
+    if (update_iterator_after_erase)
+      dragging_panel_original_iterator_ = panels_.end();
+    // No need to refresh layout as the remaining panels are unaffected.
+    // Just check if other panels can now fit in the freed up space.
+    panel_manager_->MovePanelsOutOfOverflowIfCanFit();
+  } else {
+    Panels::iterator iter = find(panels_.begin(), panels_.end(), panel);
+    DCHECK(iter != panels_.end());
+    iter = panels_.erase(iter);
+    if (update_iterator_after_erase)
+      dragging_panel_original_iterator_ = iter;
     RefreshLayout();
-
-  return true;
+  }
 }
 
 bool DockedPanelStrip::CanShowPanelAsActive(const Panel* panel) const {
@@ -443,6 +430,10 @@ void DockedPanelStrip::RestorePanel(Panel* panel) {
   panel->SetExpansionState(Panel::EXPANDED);
 }
 
+bool DockedPanelStrip::IsPanelMinimized(const Panel* panel) const {
+  return panel->expansion_state() != Panel::EXPANDED;
+}
+
 void DockedPanelStrip::IncrementMinimizedPanels() {
   minimized_panel_count_++;
   if (minimized_panel_count_ == 1)
@@ -680,6 +671,29 @@ void DockedPanelStrip::OnFullScreenModeChanged(bool is_full_screen) {
   }
 }
 
+bool DockedPanelStrip::CanFitPanel(const Panel* panel) const {
+  int width = panel->GetRestoredBounds().width();
+  return GetRightMostAvailablePosition() - width >= display_area_.x();
+}
+
+int DockedPanelStrip::FitPanelWithWidth(int width) {
+  int x = GetRightMostAvailablePosition() - width;
+  if (x < display_area_.x()) {
+    // Insufficient space for the requested width. Bump panels to overflow.
+    Panel* last_panel_to_send_to_overflow;
+    for (Panels::reverse_iterator iter = panels_.rbegin();
+         iter != panels_.rend(); ++iter) {
+      last_panel_to_send_to_overflow = *iter;
+      x = last_panel_to_send_to_overflow->GetRestoredBounds().right() - width;
+      if (x >= display_area_.x()) {
+        panel_manager_->MovePanelsToOverflow(last_panel_to_send_to_overflow);
+        break;
+      }
+    }
+  }
+  return x;
+}
+
 void DockedPanelStrip::RefreshLayout() {
   int rightmost_position = StartingRightPosition();
 
@@ -706,40 +720,16 @@ void DockedPanelStrip::RefreshLayout() {
 
   // Add/remove panels from/to overflow. A change in work area or the
   // resize/removal of a panel may affect how many panels fit in the strip.
-  OverflowPanelStrip* overflow_strip = panel_manager_->overflow_strip();
-  if (panel_iter != panels_.end()) {
-    // Prevent layout refresh when panel is removed from this strip.
-    disable_layout_refresh_ = true;
-
-    // Keep track of panels to move to overflow in a separate storage since
-    // removing it from the list will invalidate the iterator.
-    std::vector<Panel*> panels_to_move_to_overflow;
-    for (; panel_iter != panels_.end(); ++panel_iter)
-      panels_to_move_to_overflow.push_back(*panel_iter);
-
-    // Move panels to overflow in reverse to maintain their order.
-    for (std::vector<Panel*>::reverse_iterator iter =
-             panels_to_move_to_overflow.rbegin();
-         iter != panels_to_move_to_overflow.rend(); ++iter) {
-      (*iter)->MoveToStrip(overflow_strip);
-    }
-
-    disable_layout_refresh_ = false;
-  } else {
-    // Attempt to add more panels from overflow to the strip.
-    Panel* overflow_panel;
-    while ((overflow_panel = overflow_strip->first_panel()) &&
-           GetRightMostAvailablePosition() >=
-               display_area_.x() + overflow_panel->restored_size().width()) {
-      overflow_panel->MoveToStrip(this);
-    }
-  }
+  if (panel_iter != panels_.end())
+    panel_manager_->MovePanelsToOverflow(*panel_iter);
+  else
+    panel_manager_->MovePanelsOutOfOverflowIfCanFit();
 }
 
 void DockedPanelStrip::DelayedMovePanelToOverflow(Panel* panel) {
   if (panels_in_temporary_layout_.erase(panel)) {
       DCHECK(panel->has_temporary_layout());
-      panel->MoveToStrip(panel_manager_->overflow_strip());
+      panel_manager_->MovePanelToStrip(panel, PanelStrip::IN_OVERFLOW);
   }
 }
 
diff --git a/chrome/browser/ui/panels/docked_panel_strip.h b/chrome/browser/ui/panels/docked_panel_strip.h
index 2fb0029..89cf565 100644
--- a/chrome/browser/ui/panels/docked_panel_strip.h
+++ b/chrome/browser/ui/panels/docked_panel_strip.h
@@ -43,7 +43,7 @@ class DockedPanelStrip : public PanelStrip,
   // Adds a panel to the strip. The panel may be a newly created panel or one
   // that is transitioning from another grouping of panels.
   virtual void AddPanel(Panel* panel) OVERRIDE;
-  virtual bool RemovePanel(Panel* panel) OVERRIDE;
+  virtual void RemovePanel(Panel* panel) OVERRIDE;
   virtual void CloseAll() OVERRIDE;
   virtual void ResizePanelWindow(
       Panel* panel,
@@ -52,6 +52,7 @@ class DockedPanelStrip : public PanelStrip,
   virtual void ActivatePanel(Panel* panel) OVERRIDE;
   virtual void MinimizePanel(Panel* panel) OVERRIDE;
   virtual void RestorePanel(Panel* panel) OVERRIDE;
+  virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
   virtual bool CanShowPanelAsActive(const Panel* panel) const OVERRIDE;
   virtual bool CanDragPanel(const Panel* panel) const OVERRIDE;
   virtual void StartDraggingPanel(Panel* panel) OVERRIDE;
@@ -78,6 +79,7 @@ class DockedPanelStrip : public PanelStrip,
   // do NOT have a temporary layout.
   int num_panels() const { return panels_.size(); }
   const Panels& panels() const { return panels_; }
+  Panel* last_panel() const { return panels_.empty() ? NULL : panels_.back(); }
 
   gfx::Rect display_area() const { return display_area_; }
 
@@ -91,6 +93,9 @@ class DockedPanelStrip : public PanelStrip,
 
   void OnFullScreenModeChanged(bool is_full_screen);
 
+  // Returns |true| if panel can fit in the dock strip.
+  bool CanFitPanel(const Panel* panel) const;
+
 #ifdef UNIT_TEST
   int num_temporary_layout_panels() const {
     return panels_in_temporary_layout_.size();
@@ -123,6 +128,12 @@ class DockedPanelStrip : public PanelStrip,
 
   int GetRightMostAvailablePosition() const;
 
+  // Determines position in strip where a panel of |width| will fit.
+  // Other panels in the strip may be moved to overflow to make room.
+  // Returns x position where a panel of |width| wide can fit.
+  // |width| is in screen coordinates.
+  int FitPanelWithWidth(int width);
+
   // Called by AddPanel() after a delay to move a newly created panel from
   // the panel strip to overflow because the panel could not fit
   // within the bounds of the panel strip. New panels are first displayed
@@ -146,10 +157,6 @@ class DockedPanelStrip : public PanelStrip,
   int minimized_panel_count_;
   bool are_titlebars_up_;
 
-  // |True| to temporarily prevent refreshing panel layout, e.g. while
-  // moving panels to overflow area to make room for a panel in this strip.
-  bool disable_layout_refresh_;
-
   // Referring to current position in |panels_| where the dragging panel
   // resides.
   Panels::iterator dragging_panel_current_iterator_;
diff --git a/chrome/browser/ui/panels/overflow_panel_strip.cc b/chrome/browser/ui/panels/overflow_panel_strip.cc
index 2eeeb90..ce4505b 100644
--- a/chrome/browser/ui/panels/overflow_panel_strip.cc
+++ b/chrome/browser/ui/panels/overflow_panel_strip.cc
@@ -5,7 +5,6 @@
 #include "chrome/browser/ui/panels/overflow_panel_strip.h"
 
 #include "base/logging.h"
-#include "chrome/browser/ui/panels/docked_panel_strip.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
 #include "chrome/browser/ui/panels/panel_mouse_watcher.h"
 #include "chrome/browser/ui/panels/panel_overflow_indicator.h"
@@ -82,7 +81,9 @@ void OverflowPanelStrip::UpdateCurrentWidth() {
 void OverflowPanelStrip::AddPanel(Panel* panel) {
   // TODO(jianli): consider using other container to improve the perf for
   // inserting to the front. http://crbug.com/106222
-  DCHECK_EQ(this, panel->panel_strip());
+  DCHECK_NE(this, panel->panel_strip());
+  panel->set_panel_strip(this);
+
   // Newly created panels that were temporarily in the panel strip
   // are added to the back of the overflow, whereas panels that are
   // bumped from the panel strip by other panels go to the front
@@ -115,14 +116,16 @@ void OverflowPanelStrip::AddPanel(Panel* panel) {
   }
 }
 
-bool OverflowPanelStrip::RemovePanel(Panel* panel) {
+void OverflowPanelStrip::RemovePanel(Panel* panel) {
+  DCHECK_EQ(this, panel->panel_strip());
+  panel->set_panel_strip(NULL);
+
   size_t index = 0;
   Panels::iterator iter = panels_.begin();
   for (; iter != panels_.end(); ++iter, ++index)
     if (*iter == panel)
       break;
-  if (iter == panels_.end())
-    return false;
+  DCHECK(iter != panels_.end());
 
   panels_.erase(iter);
   DoRefresh(index, panels_.size() - 1);
@@ -136,8 +139,6 @@ bool OverflowPanelStrip::RemovePanel(Panel* panel) {
     overflow_indicator_.reset();
   else
     UpdateOverflowIndicatorCount();
-
-  return true;
 }
 
 void OverflowPanelStrip::CloseAll() {
@@ -164,9 +165,8 @@ void OverflowPanelStrip::OnPanelAttentionStateChanged(Panel* panel) {
 void OverflowPanelStrip::ActivatePanel(Panel* panel) {
   DCHECK_EQ(this, panel->panel_strip());
   // Activating an overflow panel moves it to the docked panel strip.
-  PanelStrip* docked_strip = panel_manager_->docked_strip();
-  panel->MoveToStrip(docked_strip);
-  docked_strip->ActivatePanel(panel);
+  panel_manager_->MovePanelToStrip(panel, PanelStrip::DOCKED);
+  panel->panel_strip()->ActivatePanel(panel);
 }
 
 void OverflowPanelStrip::MinimizePanel(Panel* panel) {
@@ -176,9 +176,13 @@ void OverflowPanelStrip::MinimizePanel(Panel* panel) {
 
 void OverflowPanelStrip::RestorePanel(Panel* panel) {
   DCHECK_EQ(this, panel->panel_strip());
-  PanelStrip* docked_strip = panel_manager_->docked_strip();
-  panel->MoveToStrip(docked_strip);
-  docked_strip->RestorePanel(panel);
+  panel_manager_->MovePanelToStrip(panel, PanelStrip::DOCKED);
+  panel->panel_strip()->RestorePanel(panel);
+}
+
+bool OverflowPanelStrip::IsPanelMinimized(const Panel* panel) const {
+  // All overflow panels are considered minimized.
+  return true;
 }
 
 bool OverflowPanelStrip::CanShowPanelAsActive(const Panel* panel) const {
diff --git a/chrome/browser/ui/panels/overflow_panel_strip.h b/chrome/browser/ui/panels/overflow_panel_strip.h
index 3ffcf5a..511b8c2 100644
--- a/chrome/browser/ui/panels/overflow_panel_strip.h
+++ b/chrome/browser/ui/panels/overflow_panel_strip.h
@@ -33,7 +33,7 @@ class OverflowPanelStrip : public PanelStrip,
   virtual void SetDisplayArea(const gfx::Rect& display_area) OVERRIDE;
   virtual void RefreshLayout() OVERRIDE;
   virtual void AddPanel(Panel* panel) OVERRIDE;
-  virtual bool RemovePanel(Panel* panel) OVERRIDE;
+  virtual void RemovePanel(Panel* panel) OVERRIDE;
   virtual void CloseAll() OVERRIDE;
   virtual void ResizePanelWindow(
       Panel* panel,
@@ -42,6 +42,7 @@ class OverflowPanelStrip : public PanelStrip,
   virtual void ActivatePanel(Panel* panel) OVERRIDE;
   virtual void MinimizePanel(Panel* panel) OVERRIDE;
   virtual void RestorePanel(Panel* panel) OVERRIDE;
+  virtual bool IsPanelMinimized(const Panel* panel) const OVERRIDE;
   virtual bool CanShowPanelAsActive(const Panel* panel) const OVERRIDE;
   virtual bool CanDragPanel(const Panel* panel) const OVERRIDE;
   virtual void StartDraggingPanel(Panel* panel) OVERRIDE;
diff --git a/chrome/browser/ui/panels/panel.cc b/chrome/browser/ui/panels/panel.cc
index 42917ce..a2e60a3 100644
--- a/chrome/browser/ui/panels/panel.cc
+++ b/chrome/browser/ui/panels/panel.cc
@@ -68,8 +68,8 @@ void Panel::Initialize(const gfx::Rect& bounds) {
 void Panel::OnNativePanelClosed() {
   if (auto_resizable_)
     native_panel_->GetPanelBrowser()->tabstrip_model()->RemoveObserver(this);
-  panel_strip_->RemovePanel(this);
   manager()->OnPanelClosed(this);
+  DCHECK(!panel_strip_);
 }
 
 PanelManager* Panel::manager() const {
@@ -77,7 +77,7 @@ PanelManager* Panel::manager() const {
 }
 
 bool Panel::draggable() const {
-  return panel_strip()->CanDragPanel(this);
+  return panel_strip_ && panel_strip_->CanDragPanel(this);
 }
 
 const Extension* Panel::GetExtension() const {
@@ -89,7 +89,7 @@ const Extension* Panel::GetExtension() const {
 // being resized vs a change in current display bounds, e.g. from overflow
 // size change. Change this when refactoring panel resize logic.
 void Panel::SetPanelBounds(const gfx::Rect& bounds) {
-  if (panel_strip_->type() == PanelStrip::DOCKED &&
+  if (panel_strip_ && panel_strip_->type() == PanelStrip::DOCKED &&
       expansion_state_ == Panel::EXPANDED)
     restored_size_ = bounds.size();
 
@@ -102,7 +102,7 @@ void Panel::SetPanelBounds(const gfx::Rect& bounds) {
 }
 
 void Panel::SetPanelBoundsInstantly(const gfx::Rect& bounds) {
-  if (panel_strip_->type() == PanelStrip::DOCKED &&
+  if (panel_strip_ && panel_strip_->type() == PanelStrip::DOCKED &&
       expansion_state_ == Panel::EXPANDED)
     restored_size_ = bounds.size();
 
@@ -156,20 +156,6 @@ void Panel::SetAppIconVisibility(bool visible) {
   native_panel_->SetPanelAppIconVisibility(visible);
 }
 
-void Panel::MoveToStrip(PanelStrip* new_strip) {
-  DCHECK_NE(panel_strip_, new_strip);
-  if (panel_strip_)
-    panel_strip_->RemovePanel(this);
-
-  panel_strip_ = new_strip;
-  panel_strip_->AddPanel(this);
-
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_PANEL_CHANGED_LAYOUT_MODE,
-      content::Source<Panel>(this),
-      content::NotificationService::NoDetails());
-}
-
 void Panel::SetExpansionState(ExpansionState new_state) {
   if (expansion_state_ == new_state)
     return;
@@ -197,7 +183,7 @@ void Panel::FullScreenModeChanged(bool is_full_screen) {
 }
 
 void Panel::Show() {
-  if (manager()->is_full_screen())
+  if (manager()->is_full_screen() || !panel_strip_)
     return;
 
   if (panel_strip_->CanShowPanelAsActive(this))
@@ -207,7 +193,7 @@ void Panel::Show() {
 }
 
 void Panel::ShowInactive() {
-  if (manager()->is_full_screen())
+  if (manager()->is_full_screen() || !panel_strip_)
     return;
 
   native_panel_->ShowPanelInactive();
@@ -225,6 +211,9 @@ void Panel::Close() {
 }
 
 void Panel::Activate() {
+  if (!panel_strip_)
+    return;
+
   panel_strip_->ActivatePanel(this);
   native_panel_->ActivatePanel();
 }
@@ -238,7 +227,7 @@ bool Panel::IsActive() const {
 }
 
 void Panel::FlashFrame(bool flash) {
-  if (IsDrawingAttention() == flash)
+  if (IsDrawingAttention() == flash || !panel_strip_)
     return;
 
   // Don't draw attention for an active panel.
@@ -323,9 +312,7 @@ bool Panel::IsMaximized() const {
 }
 
 bool Panel::IsMinimized() const {
-  PanelStrip::Type strip_type = panel_strip_->type();
-  return strip_type == PanelStrip::IN_OVERFLOW ||
-      (strip_type == PanelStrip::DOCKED && expansion_state_ != EXPANDED);
+  return !panel_strip_ || panel_strip()->IsPanelMinimized(this);
 }
 
 void Panel::Maximize() {
@@ -333,11 +320,13 @@ void Panel::Maximize() {
 }
 
 void Panel::Minimize() {
-  panel_strip_->MinimizePanel(this);
+  if (panel_strip_)
+    panel_strip_->MinimizePanel(this);
 }
 
 void Panel::Restore() {
-  panel_strip_->RestorePanel(this);
+  if (panel_strip_)
+    panel_strip_->RestorePanel(this);
 }
 
 void Panel::EnterFullscreen(
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index 96a5be9..495f05c 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -221,9 +221,8 @@ class Panel : public BrowserWindow,
   // May be NULL if panel is newly created and has not been positioned yet.
   PanelStrip* panel_strip() const { return panel_strip_; }
 
-  // Moves the panel to the |new_strip|, removing the panel from its
-  // current strip.
-  void MoveToStrip(PanelStrip* new_strip);
+  // Sets the current panel strip that contains this panel.
+  void set_panel_strip(PanelStrip* new_strip) { panel_strip_ = new_strip; }
 
   ExpansionState expansion_state() const { return expansion_state_; }
   ExpansionState old_expansion_state() const { return old_expansion_state_; }
diff --git a/chrome/browser/ui/panels/panel_manager.cc b/chrome/browser/ui/panels/panel_manager.cc
index bb8323a..22195b6 100644
--- a/chrome/browser/ui/panels/panel_manager.cc
+++ b/chrome/browser/ui/panels/panel_manager.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/ui/panels/panel_manager.h"
 
+#include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -64,7 +65,8 @@ bool PanelManager::ShouldUsePanels(const std::string& extension_id) {
 PanelManager::PanelManager()
     : panel_mouse_watcher_(PanelMouseWatcher::Create()),
       auto_sizing_enabled_(true),
-      is_full_screen_(false) {
+      is_full_screen_(false),
+      is_processing_overflow_(false) {
   detached_strip_.reset(new DetachedPanelStrip(this));
   docked_strip_.reset(new DockedPanelStrip(this));
   overflow_strip_.reset(new OverflowPanelStrip(this));
@@ -117,7 +119,7 @@ Panel* PanelManager::CreatePanel(Browser* browser) {
   int width = browser->override_bounds().width();
   int height = browser->override_bounds().height();
   Panel* panel = new Panel(browser, gfx::Size(width, height));
-  panel->MoveToStrip(docked_strip_.get());
+  docked_strip_->AddPanel(panel);
 
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_PANEL_ADDED,
@@ -147,10 +149,11 @@ void PanelManager::CheckFullScreenMode() {
 }
 
 void PanelManager::OnPanelClosed(Panel* panel) {
-  if (num_panels() == 0)
+  if (num_panels() == 1)
     full_screen_mode_timer_.Stop();
 
   drag_controller_->OnPanelClosed(panel);
+  panel->panel_strip()->RemovePanel(panel);
 
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_PANEL_CLOSED,
@@ -185,6 +188,59 @@ void PanelManager::ResizePanel(Panel* panel, const gfx::Size& new_size) {
   panel->SetAutoResizable(false);
 }
 
+void PanelManager::MovePanelToStrip(Panel* panel,
+                                    PanelStrip::Type new_layout) {
+  DCHECK(panel);
+  PanelStrip* current_strip = panel->panel_strip();
+  DCHECK(current_strip);
+  DCHECK_NE(current_strip->type(), new_layout);
+  current_strip->RemovePanel(panel);
+
+  PanelStrip* target_strip = NULL;
+  switch (new_layout) {
+    case PanelStrip::DETACHED:
+      target_strip = detached_strip_.get();
+      break;
+    case PanelStrip::DOCKED:
+      target_strip = docked_strip_.get();
+      break;
+    case PanelStrip::IN_OVERFLOW:
+      target_strip = overflow_strip_.get();
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  target_strip->AddPanel(panel);
+
+  content::NotificationService::current()->Notify(
+      chrome::NOTIFICATION_PANEL_CHANGED_LAYOUT_MODE,
+      content::Source<Panel>(panel),
+      content::NotificationService::NoDetails());
+}
+
+void PanelManager::MovePanelsToOverflow(Panel* last_panel_to_move) {
+  AutoReset<bool> processing_overflow(&is_processing_overflow_, true);
+  // Move panels to overflow in reverse to maintain their order.
+  Panel* bumped_panel;
+  while ((bumped_panel = docked_strip_->last_panel())) {
+    MovePanelToStrip(bumped_panel, PanelStrip::IN_OVERFLOW);
+    if (bumped_panel == last_panel_to_move)
+      break;
+  }
+  DCHECK(!docked_strip_->panels().empty());
+}
+
+void PanelManager::MovePanelsOutOfOverflowIfCanFit() {
+  if (is_processing_overflow_)
+    return;
+
+  Panel* overflow_panel;
+  while ((overflow_panel = overflow_strip_->first_panel()) &&
+         docked_strip_->CanFitPanel(overflow_panel))
+    MovePanelToStrip(overflow_panel, PanelStrip::DOCKED);
+}
+
 bool PanelManager::ShouldBringUpTitlebars(int mouse_x, int mouse_y) const {
   return docked_strip_->ShouldBringUpTitlebars(mouse_x, mouse_y);
 }
diff --git a/chrome/browser/ui/panels/panel_manager.h b/chrome/browser/ui/panels/panel_manager.h
index 73202a6..3194cf8 100644
--- a/chrome/browser/ui/panels/panel_manager.h
+++ b/chrome/browser/ui/panels/panel_manager.h
@@ -13,6 +13,7 @@
 #include "base/timer.h"
 #include "chrome/browser/ui/panels/auto_hiding_desktop_bar.h"
 #include "chrome/browser/ui/panels/panel.h"
+#include "chrome/browser/ui/panels/panel_strip.h"
 #include "ui/gfx/rect.h"
 
 class Browser;
@@ -61,6 +62,15 @@ class PanelManager : public AutoHidingDesktopBar::Observer {
   // for panels that are auto-sized.
   void ResizePanel(Panel* panel, const gfx::Size& new_size);
 
+  // Moves the |panel| to a different type of panel strip.
+  void MovePanelToStrip(Panel* panel, PanelStrip::Type new_layout);
+
+  // Move all panels up to, and including, the |last_panel_to_move| to overflow.
+  void MovePanelsToOverflow(Panel* last_panel_to_move);
+
+  // Moves as many panels out of overflow as space allows.
+  void MovePanelsOutOfOverflowIfCanFit();
+
   // Returns true if we should bring up the titlebars, given the current mouse
   // point.
   bool ShouldBringUpTitlebars(int mouse_x, int mouse_y) const;
@@ -211,6 +221,10 @@ class PanelManager : public AutoHidingDesktopBar::Observer {
   // True if current active app is in full screen mode.
   bool is_full_screen_;
 
+  // True only while moving panels to overflow. Used to prevent moving panels
+  // out of overflow while in the process of moving panels to overflow.
+  bool is_processing_overflow_;
+
   DISALLOW_COPY_AND_ASSIGN(PanelManager);
 };
 
diff --git a/chrome/browser/ui/panels/panel_overflow_browsertest.cc b/chrome/browser/ui/panels/panel_overflow_browsertest.cc
index e5b9961..14699bd 100644
--- a/chrome/browser/ui/panels/panel_overflow_browsertest.cc
+++ b/chrome/browser/ui/panels/panel_overflow_browsertest.cc
@@ -254,9 +254,9 @@ IN_PROC_BROWSER_TEST_F(PanelOverflowBrowserTest, UpdateDraggableStatus) {
   PanelManager* panel_manager = PanelManager::GetInstance();
   Panel* panel = CreatePanel("panel");
   EXPECT_TRUE(panel->draggable());
-  panel->MoveToStrip(panel_manager->overflow_strip());
+  panel_manager->MovePanelToStrip(panel, PanelStrip::IN_OVERFLOW);
   EXPECT_FALSE(panel->draggable());
-  panel->MoveToStrip(panel_manager->docked_strip());
+  panel_manager->MovePanelToStrip(panel, PanelStrip::DOCKED);
   EXPECT_TRUE(panel->draggable());
   panel->Close();
 }
diff --git a/chrome/browser/ui/panels/panel_strip.h b/chrome/browser/ui/panels/panel_strip.h
index 7b0bced..c1da8f4 100644
--- a/chrome/browser/ui/panels/panel_strip.h
+++ b/chrome/browser/ui/panels/panel_strip.h
@@ -36,8 +36,7 @@ class PanelStrip {
 
   // Removes |panel| from the collection of panels. Invoked asynchronously
   // after a panel has been closed.
-  // Returns |false| if the panel is not in the strip.
-  virtual bool RemovePanel(Panel* panel) = 0;
+  virtual void RemovePanel(Panel* panel) = 0;
 
   // Closes all panels in the collection. Panels will be removed after closing.
   virtual void CloseAll() = 0;
@@ -62,6 +61,8 @@ class PanelStrip {
   virtual void MinimizePanel(Panel* panel) = 0;
   virtual void RestorePanel(Panel* panel) = 0;
 
+  virtual bool IsPanelMinimized(const Panel* panel) const = 0;
+
   // Returns true if |panel| can be shown as active.
   virtual bool CanShowPanelAsActive(const Panel* panel) const = 0;