Refactor PanelManager to create PanelStrip.

chrome/browser/ui/panels/panel_manager.cc

Index: chrome/browser/ui/panels/panel_manager.cc
diff --git a/chrome/browser/ui/panels/panel_manager.cc b/chrome/browser/ui/panels/panel_manager.cc
index 7e2fefdbb4373ca3532e2acbc32a02ad43a3792a..ae5bbe22801b42eaf74ecd6ded6ad688ff0ced65 100644
--- a/chrome/browser/ui/panels/panel_manager.cc
+++ b/chrome/browser/ui/panels/panel_manager.cc
@@ -4,55 +4,28 @@
 
 #include "chrome/browser/ui/panels/panel_manager.h"
 
-#include <algorithm>
-
-#include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/message_loop.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/panels/panel_mouse_watcher.h"
+#include "chrome/browser/ui/panels/panel_strip.h"
 #include "chrome/browser/ui/window_sizer.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 
 namespace {
-// Invalid panel index.
-const size_t kInvalidPanelIndex = static_cast<size_t>(-1);
-
-// Width of spacing between first panel and the right edge of the screen.
-// Leaving a larger gap at the edge of the screen allows access to UI
-// elements located on the bottom right of windows.
-const int kRightScreenEdgeSpacingWidth = 24;
-
-// Width to height ratio is used to compute the default width or height
-// when only one value is provided.
-const double kPanelDefaultWidthToHeightRatio = 1.62;  // golden ratio
-
-// Maxmium width and height of a panel based on the factor of the working
-// area.
-const double kPanelMaxWidthFactor = 0.35;
-const double kPanelMaxHeightFactor = 0.5;
-
-// Occasionally some system, like Windows, might not bring up or down the bottom
-// bar when the mouse enters or leaves the bottom screen area. This is the
-// maximum time we will wait for the bottom bar visibility change notification.
-// After the time expires, we bring up/down the titlebars as planned.
-const int kMaxMillisecondsWaitForBottomBarVisibilityChange = 1000;
-
-// See usage below.
-#if defined(TOOLKIT_GTK)
-const int kMillisecondsBeforeCollapsingFromTitleOnlyState = 2000;
-#else
-const int kMillisecondsBeforeCollapsingFromTitleOnlyState = 0;
-#endif
-}  // namespace
+const int kOverflowStripThickness = 24;
 
-// static
-const int PanelManager::kPanelMinWidth = 100;
-const int PanelManager::kPanelMinHeight = 20;
+// Width of spacing around panel strip and the left/right edges of the screen.
+const int kPanelStripLeftMargin = kOverflowStripThickness + 6;
+const int kPanelStripRightMargin = 24;
+
+// Height of panel strip is based on the factor of the working area.
+const double kPanelStripHeightFactor = 0.5;
+
+}  // namespace
 
 // static
 PanelManager* PanelManager::GetInstance() {
@@ -61,24 +34,14 @@ PanelManager* PanelManager::GetInstance() {
 }
 
 PanelManager::PanelManager()
-    : minimized_panel_count_(0),
-      are_titlebars_up_(false),
-      dragging_panel_index_(kInvalidPanelIndex),
-      dragging_panel_original_x_(0),
-      delayed_titlebar_action_(NO_ACTION),
-      remove_delays_for_testing_(false),
-      titlebar_action_factory_(this),
-      auto_sizing_enabled_(true),
-      mouse_watching_disabled_(false) {
-  panel_mouse_watcher_.reset(PanelMouseWatcher::Create());
+    : panel_mouse_watcher_(PanelMouseWatcher::Create()),
+      auto_sizing_enabled_(true) {
+  panel_strip_.reset(new PanelStrip(this));
   auto_hiding_desktop_bar_ = AutoHidingDesktopBar::Create(this);
   OnDisplayChanged();
 }
 
 PanelManager::~PanelManager() {
-  DCHECK(panels_.empty());
-  DCHECK(panels_pending_to_remove_.empty());
-  DCHECK_EQ(0, minimized_panel_count_);
 }
 
 void PanelManager::OnDisplayChanged() {
@@ -101,51 +64,26 @@ void PanelManager::SetWorkArea(const gfx::Rect& work_area) {
 
   auto_hiding_desktop_bar_->UpdateWorkArea(work_area_);
   AdjustWorkAreaForAutoHidingDesktopBars();
+  Layout();
+}
 
-  Rearrange(panels_.begin(), StartingRightPosition());
+void PanelManager::Layout() {
+  int height =
+      static_cast<int>(adjusted_work_area_.height() * kPanelStripHeightFactor);
+  gfx::Rect panel_strip_bounds;
+  panel_strip_bounds.set_x(adjusted_work_area_.x() + kPanelStripLeftMargin);
+  panel_strip_bounds.set_y(adjusted_work_area_.bottom() - height);
+  panel_strip_bounds.set_width(adjusted_work_area_.width() -
+                               kPanelStripLeftMargin - kPanelStripRightMargin);
+  panel_strip_bounds.set_height(height);
+  panel_strip_->SetBounds(panel_strip_bounds);
 }
 
 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));
-
-  int max_panel_width = GetMaxPanelWidth();
-  int max_panel_height = GetMaxPanelHeight();
-  panel->SetSizeRange(gfx::Size(kPanelMinWidth, kPanelMinHeight),
-                      gfx::Size(max_panel_width, max_panel_height));
-
-  // Auto resizable is enabled only if no initial size is provided.
-  bool auto_resize = (width == 0 && height == 0);
-  panel->SetAutoResizable(auto_resize);
-
-  // Adjust the width and height to fit into our constraint.
-  if (!auto_resize) {
-    if (height == 0)
-      height = width / kPanelDefaultWidthToHeightRatio;
-    if (width == 0)
-      width = height * kPanelDefaultWidthToHeightRatio;
-  }
-
-  if (width < kPanelMinWidth)
-    width = kPanelMinWidth;
-  else if (width > max_panel_width)
-    width = max_panel_width;
-
-  if (height < kPanelMinHeight)
-    height = kPanelMinHeight;
-  else if (height > max_panel_height)
-    height = max_panel_height;
-
-  panel->set_restored_size(gfx::Size(width, height));
-
-  // Layout the new panel.
-  int y = adjusted_work_area_.bottom() - height;
-  int x = GetRightMostAvailablePosition() - width;
-  panel->Initialize(gfx::Rect(x, y, width, height));
-
-  panels_.push_back(panel);
+  panel_strip_->AddPanel(panel);
 
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_PANEL_ADDED,
@@ -155,50 +93,17 @@ Panel* PanelManager::CreatePanel(Browser* browser) {
   return panel;
 }
 
-int PanelManager::GetMaxPanelWidth() const {
-  return static_cast<int>(adjusted_work_area_.width() * kPanelMaxWidthFactor);
-}
-
-int PanelManager::GetMaxPanelHeight() const {
-  return static_cast<int>(adjusted_work_area_.height() * kPanelMaxHeightFactor);
-}
-
 int PanelManager::StartingRightPosition() const {
-  return adjusted_work_area_.right() - kRightScreenEdgeSpacingWidth;
-}
-
-int PanelManager::GetRightMostAvailablePosition() const {
-  return panels_.empty() ? StartingRightPosition() :
-      (panels_.back()->GetBounds().x() - kPanelsHorizontalSpacing);
+  return panel_strip_->StartingRightPosition();
 }
 
 void PanelManager::Remove(Panel* panel) {
-  // If we're in the process of dragging, delay the removal.
-  if (dragging_panel_index_ != kInvalidPanelIndex) {
-    panels_pending_to_remove_.push_back(panel);
+  if (panel_strip_->Remove(panel))
     return;
-  }
-
-  DoRemove(panel);
-}
-
-void PanelManager::DelayedRemove() {
-  for (size_t i = 0; i < panels_pending_to_remove_.size(); ++i)
-    DoRemove(panels_pending_to_remove_[i]);
-  panels_pending_to_remove_.clear();
+  // TODO(jianli): else try removing from overflow strip
 }
 
-void PanelManager::DoRemove(Panel* panel) {
-  Panels::iterator iter = find(panels_.begin(), panels_.end(), panel);
-  if (iter == panels_.end())
-    return;
-
-  if (panel->expansion_state() != Panel::EXPANDED)
-    DecrementMinimizedPanels();
-
-  gfx::Rect bounds = (*iter)->GetBounds();
-  Rearrange(panels_.erase(iter), bounds.right());
-
+void PanelManager::OnPanelRemoved(Panel* panel) {
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_PANEL_REMOVED,
       content::Source<Panel>(panel),
@@ -206,337 +111,35 @@ void PanelManager::DoRemove(Panel* panel) {
 }
 
 void PanelManager::StartDragging(Panel* panel) {
-  for (size_t i = 0; i < panels_.size(); ++i) {
-    if (panels_[i] == panel) {
-      dragging_panel_index_ = i;
-      dragging_panel_bounds_ = panel->GetBounds();
-      dragging_panel_original_x_ = dragging_panel_bounds_.x();
-      break;
-    }
-  }
+  panel_strip_->StartDragging(panel);
 }
 
 void PanelManager::Drag(int delta_x) {
-  DCHECK(dragging_panel_index_ != kInvalidPanelIndex);
-
-  if (!delta_x)
-    return;
-
-  // Moves this panel to the dragging position.
-  Panel* dragging_panel = panels_[dragging_panel_index_];
-  gfx::Rect new_bounds(dragging_panel->GetBounds());
-  new_bounds.set_x(new_bounds.x() + delta_x);
-  dragging_panel->SetPanelBounds(new_bounds);
-
-  // Checks and processes other affected panels.
-  if (delta_x > 0)
-    DragRight();
-  else
-    DragLeft();
-}
-
-void PanelManager::DragLeft() {
-  Panel* dragging_panel = panels_[dragging_panel_index_];
-
-  // This is the left corner of the dragging panel. We use it to check against
-  // all the panels on its left.
-  int dragging_panel_left_boundary = dragging_panel->GetBounds().x();
-
-  // This is the right corner which a panel will be moved to.
-  int current_panel_right_boundary =
-      dragging_panel_bounds_.x() + dragging_panel_bounds_.width();
-
-  // Checks the panels to the left of the dragging panel.
-  size_t current_panel_index = dragging_panel_index_ + 1;
-  for (; current_panel_index < panels_.size(); ++current_panel_index) {
-    Panel* current_panel = panels_[current_panel_index];
-
-    // Current panel will only be affected if the left corner of dragging
-    // panel goes beyond the middle position of the current panel.
-    if (dragging_panel_left_boundary > current_panel->GetBounds().x() +
-            current_panel->GetBounds().width() / 2)
-      break;
-
-    // Moves current panel to the new position.
-    gfx::Rect bounds(current_panel->GetBounds());
-    bounds.set_x(current_panel_right_boundary - bounds.width());
-    current_panel_right_boundary -= bounds.width() + kPanelsHorizontalSpacing;
-    current_panel->SetPanelBounds(bounds);
-
-    // Updates the index of current panel since it has been moved to the
-    // position of previous panel.
-    panels_[current_panel_index - 1] = current_panel;
-  }
-
-  // Updates the position and index of dragging panel as the result of moving
-  // other affected panels.
-  if (current_panel_index != dragging_panel_index_ + 1) {
-    dragging_panel_bounds_.set_x(current_panel_right_boundary -
-                                 dragging_panel_bounds_.width());
-    dragging_panel_index_ = current_panel_index - 1;
-    panels_[dragging_panel_index_] = dragging_panel;
-  }
-}
-
-void PanelManager::DragRight() {
-  Panel* dragging_panel = panels_[dragging_panel_index_];
-
-  // This is the right corner of the dragging panel. We use it to check against
-  // all the panels on its right.
-  int dragging_panel_right_boundary = dragging_panel->GetBounds().x() +
-      dragging_panel->GetBounds().width() - 1;
-
-  // This is the left corner which a panel will be moved to.
-  int current_panel_left_boundary = dragging_panel_bounds_.x();
-
-  // Checks the panels to the right of the dragging panel.
-  int current_panel_index = static_cast<int>(dragging_panel_index_) - 1;
-  for (; current_panel_index >= 0; --current_panel_index) {
-    Panel* current_panel = panels_[current_panel_index];
-
-    // Current panel will only be affected if the right corner of dragging
-    // panel goes beyond the middle position of the current panel.
-    if (dragging_panel_right_boundary < current_panel->GetBounds().x() +
-            current_panel->GetBounds().width() / 2)
-      break;
-
-    // Moves current panel to the new position.
-    gfx::Rect bounds(current_panel->GetBounds());
-    bounds.set_x(current_panel_left_boundary);
-    current_panel_left_boundary += bounds.width() + kPanelsHorizontalSpacing;
-    current_panel->SetPanelBounds(bounds);
-
-    // Updates the index of current panel since it has been moved to the
-    // position of previous panel.
-    panels_[current_panel_index + 1] = current_panel;
-  }
-
-  // Updates the position and index of dragging panel as the result of moving
-  // other affected panels.
-  if (current_panel_index != static_cast<int>(dragging_panel_index_) - 1) {
-    dragging_panel_bounds_.set_x(current_panel_left_boundary);
-    dragging_panel_index_ = current_panel_index + 1;
-    panels_[dragging_panel_index_] = dragging_panel;
-  }
+  panel_strip_->Drag(delta_x);
 }
 
 void PanelManager::EndDragging(bool cancelled) {
-  DCHECK(dragging_panel_index_ != kInvalidPanelIndex);
-
-  if (cancelled) {
-    Drag(dragging_panel_original_x_ -
-         panels_[dragging_panel_index_]->GetBounds().x());
-  } else {
-    panels_[dragging_panel_index_]->SetPanelBounds(
-        dragging_panel_bounds_);
-  }
-
-  dragging_panel_index_ = kInvalidPanelIndex;
-
-  DelayedRemove();
+  panel_strip_->EndDragging(cancelled);
 }
 
 void PanelManager::OnPanelExpansionStateChanged(
     Panel::ExpansionState old_state, Panel::ExpansionState new_state) {
-  DCHECK_NE(new_state, old_state);
-  switch (new_state) {
-    case Panel::EXPANDED:
-      DecrementMinimizedPanels();
-      break;
-    case Panel::MINIMIZED:
-    case Panel::TITLE_ONLY:
-      if (old_state == Panel::EXPANDED)
-        IncrementMinimizedPanels();
-      break;
-    default:
-      break;
-  }
-}
-
-void PanelManager::IncrementMinimizedPanels() {
-  if (!mouse_watching_disabled_ && !minimized_panel_count_)
-    panel_mouse_watcher_->AddObserver(this);
-  minimized_panel_count_++;
-  DCHECK_LE(minimized_panel_count_, num_panels());
-}
-
-void PanelManager::DecrementMinimizedPanels() {
-  minimized_panel_count_--;
-  DCHECK_GE(minimized_panel_count_, 0);
-  if (!mouse_watching_disabled_ && !minimized_panel_count_)
-    panel_mouse_watcher_->RemoveObserver(this);
+  panel_strip_->OnPanelExpansionStateChanged(old_state, new_state);
 }
 
 void PanelManager::OnPreferredWindowSizeChanged(
     Panel* panel, const gfx::Size& preferred_window_size) {
   if (!auto_sizing_enabled_)
     return;
-
-  gfx::Rect bounds = panel->GetBounds();
-
-  // The panel width:
-  // * cannot grow or shrink to go beyond [min_width, max_width]
-  int new_width = preferred_window_size.width();
-  if (new_width > panel->max_size().width())
-    new_width = panel->max_size().width();
-  if (new_width < panel->min_size().width())
-    new_width = panel->min_size().width();
-
-  if (new_width != bounds.width()) {
-    int delta = bounds.width() - new_width;
-    bounds.set_x(bounds.x() + delta);
-    bounds.set_width(new_width);
-
-    // Reposition all the panels on the left.
-    int panel_index = -1;
-    for (int i = 0; i < static_cast<int>(panels_.size()); ++i) {
-      if (panels_[i] == panel) {
-        panel_index = i;
-        break;
-      }
-    }
-    DCHECK(panel_index >= 0);
-    for (int i = static_cast<int>(panels_.size()) -1; i > panel_index;
-         --i) {
-      gfx::Rect this_bounds = panels_[i]->GetBounds();
-      this_bounds.set_x(this_bounds.x() + delta);
-      panels_[i]->SetPanelBounds(this_bounds);
-    }
-  }
-
-  // The panel height:
-  // * cannot grow or shrink to go beyond [min_height, max_height]
-  int new_height = preferred_window_size.height();
-  if (new_height > panel->max_size().height())
-    new_height = panel->max_size().height();
-  if (new_height < panel->min_size().height())
-    new_height = panel->min_size().height();
-
-  // Only need to adjust bounds height when panel is expanded.
-  gfx::Size restored_size = panel->restored_size();
-  if (new_height != restored_size.height() &&
-      panel->expansion_state() == Panel::EXPANDED) {
-    bounds.set_y(bounds.y() - new_height + bounds.height());
-    bounds.set_height(new_height);
-  }
-
-  gfx::Size new_size = gfx::Size(new_width, new_height);
-  if (new_size != restored_size)
-    panel->set_restored_size(new_size);
-
-  panel->SetPanelBounds(bounds);
+  panel_strip_->OnPreferredWindowSizeChanged(panel, preferred_window_size);
 }
 
 bool PanelManager::ShouldBringUpTitlebars(int mouse_x, int mouse_y) const {
-  // We should always bring up the titlebar if the mouse is over the
-  // visible auto-hiding bottom bar.
-  if (auto_hiding_desktop_bar_->IsEnabled(AutoHidingDesktopBar::ALIGN_BOTTOM) &&
-      auto_hiding_desktop_bar_->GetVisibility(
-              AutoHidingDesktopBar::ALIGN_BOTTOM) ==
-          AutoHidingDesktopBar::VISIBLE &&
-      mouse_y >= adjusted_work_area_.bottom())
-    return true;
-
-  for (Panels::const_iterator iter = panels_.begin();
-       iter != panels_.end(); ++iter) {
-    if ((*iter)->ShouldBringUpTitlebar(mouse_x, mouse_y))
-      return true;
-  }
-  return false;
+  return panel_strip_->ShouldBringUpTitlebars(mouse_x, mouse_y);
 }
 
 void PanelManager::BringUpOrDownTitlebars(bool bring_up) {
-  if (are_titlebars_up_ == bring_up)
-    return;
-  are_titlebars_up_ = bring_up;
-
-  int task_delay_milliseconds = 0;
-
-  // If the auto-hiding bottom bar exists, delay the action until the bottom
-  // bar is fully visible or hidden. We do not want both bottom bar and panel
-  // titlebar to move at the same time but with different speeds.
-  if (auto_hiding_desktop_bar_->IsEnabled(AutoHidingDesktopBar::ALIGN_BOTTOM)) {
-    AutoHidingDesktopBar::Visibility visibility = auto_hiding_desktop_bar_->
-        GetVisibility(AutoHidingDesktopBar::ALIGN_BOTTOM);
-    if (visibility != (bring_up ? AutoHidingDesktopBar::VISIBLE
-                                : AutoHidingDesktopBar::HIDDEN)) {
-      // Occasionally some system, like Windows, might not bring up or down the
-      // bottom bar when the mouse enters or leaves the bottom screen area.
-      // Thus, we schedule a delayed task to do the work if we do not receive
-      // the bottom bar visibility change notification within a certain period
-      // of time.
-      task_delay_milliseconds =
-          kMaxMillisecondsWaitForBottomBarVisibilityChange;
-    }
-  }
-
-  // On some OSes, the interaction with native Taskbars/Docks may be improved
-  // if the panels do not go back to minimized state too fast. For example,
-  // it makes it possible to hit the titlebar on OSX if Dock has Magnifying
-  // enabled - the panels stay up for a while after Dock magnification effect
-  // stops covering the panels.
-  //
-  // Another example would be taskbar in auto-hide mode on Linux. In this mode
-  // taskbar will cover the panel in title hover mode, leaving it up for a few
-  // seconds would allow the user to be able to click on it.
-  //
-  // Currently, no platforms use both delays.
-  DCHECK(task_delay_milliseconds == 0);
-  if (!bring_up)
-    task_delay_milliseconds = kMillisecondsBeforeCollapsingFromTitleOnlyState;
-
-  // OnAutoHidingDesktopBarVisibilityChanged will handle this.
-  delayed_titlebar_action_ = bring_up ? BRING_UP : BRING_DOWN;
-  if (remove_delays_for_testing_)
-    task_delay_milliseconds = 0;
-
-  // If user moves the mouse in and out of mouse tracking area, we might have
-  // previously posted but not yet dispatched task in the queue. New action
-  // should always 'reset' the delays so cancel any tasks that haven't run yet
-  // and post a new one.
-  titlebar_action_factory_.InvalidateWeakPtrs();
-  MessageLoop::current()->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(&PanelManager::DelayedBringUpOrDownTitlebarsCheck,
-                 titlebar_action_factory_.GetWeakPtr()),
-      task_delay_milliseconds);
-}
-
-void PanelManager::DelayedBringUpOrDownTitlebarsCheck() {
-  // Task was already processed or cancelled - bail out.
-  if (delayed_titlebar_action_ == NO_ACTION)
-    return;
-
-  bool need_to_bring_up_titlebars = (delayed_titlebar_action_ == BRING_UP);
-
-  delayed_titlebar_action_ = NO_ACTION;
-
-  // Check if the action is still needed based on the latest mouse position. The
-  // user could move the mouse into the tracking area and then quickly move it
-  // out of the area. In case of this, cancel the action.
-  if (are_titlebars_up_ != need_to_bring_up_titlebars)
-    return;
-
-  DoBringUpOrDownTitlebars(need_to_bring_up_titlebars);
-}
-
-void PanelManager::DoBringUpOrDownTitlebars(bool bring_up) {
-  for (Panels::const_iterator iter = panels_.begin();
-       iter != panels_.end(); ++iter) {
-    Panel* panel = *iter;
-
-    // Skip any panel that is drawing the attention.
-    if (panel->IsDrawingAttention())
-      continue;
-
-    if (bring_up) {
-      if (panel->expansion_state() == Panel::MINIMIZED)
-        panel->SetExpansionState(Panel::TITLE_ONLY);
-    } else {
-      if (panel->expansion_state() == Panel::TITLE_ONLY)
-        panel->SetExpansionState(Panel::MINIMIZED);
-    }
-  }
+  panel_strip_->BringUpOrDownTitlebars(bring_up);
 }
 
 void PanelManager::AdjustWorkAreaForAutoHidingDesktopBars() {
@@ -558,16 +161,7 @@ void PanelManager::AdjustWorkAreaForAutoHidingDesktopBars() {
 
 int PanelManager::GetBottomPositionForExpansionState(
     Panel::ExpansionState expansion_state) const {
-  int bottom = adjusted_work_area_.bottom();
-  // If there is an auto-hiding desktop bar aligned to the bottom edge, we need
-  // to move the title-only panel above the auto-hiding desktop bar.
-  if (expansion_state == Panel::TITLE_ONLY &&
-      auto_hiding_desktop_bar_->IsEnabled(AutoHidingDesktopBar::ALIGN_BOTTOM)) {
-    bottom -= auto_hiding_desktop_bar_->GetThickness(
-        AutoHidingDesktopBar::ALIGN_BOTTOM);
-  }
-
-  return bottom;
+  return panel_strip_->GetBottomPositionForExpansionState(expansion_state);
 }
 
 BrowserWindow* PanelManager::GetNextBrowserWindowToActivate(
@@ -584,70 +178,35 @@ BrowserWindow* PanelManager::GetNextBrowserWindowToActivate(
   return NULL;
 }
 
-void PanelManager::MoveToPanelStrip(Panel* panel) {
-  // TODO(jennb) - implement.
-}
-
 void PanelManager::MoveToOverflowStrip(Panel* panel, bool is_new) {
   // TODO(jianli) - implement.
 }
 
-void PanelManager::OnMouseMove(const gfx::Point& mouse_position) {
-  bool bring_up_titlebars = ShouldBringUpTitlebars(mouse_position.x(),
-                                                   mouse_position.y());
-  BringUpOrDownTitlebars(bring_up_titlebars);
-}
-
 void PanelManager::OnAutoHidingDesktopBarThicknessChanged() {
   AdjustWorkAreaForAutoHidingDesktopBars();
-  Rearrange(panels_.begin(), StartingRightPosition());
+  Layout();
 }
 
 void PanelManager::OnAutoHidingDesktopBarVisibilityChanged(
     AutoHidingDesktopBar::Alignment alignment,
     AutoHidingDesktopBar::Visibility visibility) {
-  if (delayed_titlebar_action_ == NO_ACTION)
-    return;
-
-  AutoHidingDesktopBar::Visibility expected_visibility =
-      delayed_titlebar_action_ == BRING_UP ? AutoHidingDesktopBar::VISIBLE
-                                           : AutoHidingDesktopBar::HIDDEN;
-  if (visibility != expected_visibility)
-    return;
-
-  DoBringUpOrDownTitlebars(delayed_titlebar_action_ == BRING_UP);
-  delayed_titlebar_action_ = NO_ACTION;
-}
-
-void PanelManager::Rearrange(Panels::iterator iter_to_start,
-                             int rightmost_position) {
-  for (Panels::iterator iter = iter_to_start; iter != panels_.end(); ++iter) {
-    Panel* panel = *iter;
-    gfx::Rect new_bounds(panel->GetBounds());
-    new_bounds.set_x(rightmost_position - new_bounds.width());
-    new_bounds.set_y(
-        GetBottomPositionForExpansionState(panel->expansion_state()) -
-            new_bounds.height());
-    if (new_bounds != panel->GetBounds())
-      panel->SetPanelBounds(new_bounds);
-
-    rightmost_position = new_bounds.x() - kPanelsHorizontalSpacing;
-  }
+  panel_strip_->OnAutoHidingDesktopBarVisibilityChanged(alignment, visibility);
 }
 
 void PanelManager::RemoveAll() {
-  // This should not be called when we're in the process of dragging.
-  DCHECK(dragging_panel_index_ == kInvalidPanelIndex);
-
-  // Make a copy of the iterator as closing panels can modify the vector.
-  Panels panels_copy = panels_;
+  panel_strip_->RemoveAll();
+  // TODO(jianli): overflow_strip_->RemoveAll();
+}
 
-  // Start from the bottom to avoid reshuffling.
-  for (Panels::reverse_iterator iter = panels_copy.rbegin();
-       iter != panels_copy.rend(); ++iter)
-    (*iter)->Close();
+int PanelManager::num_panels() const {
+  return panel_strip_->num_panels();
+  // TODO(jianli): + overflow_strip_->num_panels();
 }
 
 bool PanelManager::is_dragging_panel() const {
-  return dragging_panel_index_ != kInvalidPanelIndex;
+  return panel_strip_->is_dragging_panel();
+}
+
+const PanelManager::Panels& PanelManager::panels() const {
+  return panel_strip_->panels();
 }