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

chrome/browser/ui/panels/overflow_panel_strip.cc

Index: chrome/browser/ui/panels/overflow_panel_strip.cc
diff --git a/chrome/browser/ui/panels/overflow_panel_strip.cc b/chrome/browser/ui/panels/overflow_panel_strip.cc
index 934d71857f9359290249de2ee8269942428b3651..3f41812f5fabdf829cd36313e453775d0e52e493 100644
--- a/chrome/browser/ui/panels/overflow_panel_strip.cc
+++ b/chrome/browser/ui/panels/overflow_panel_strip.cc
@@ -82,7 +82,9 @@ 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->SetPanelStrip(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 +117,14 @@ void OverflowPanelStrip::AddPanel(Panel* panel) {
   }
 }
 
-bool OverflowPanelStrip::RemovePanel(Panel* panel) {
+void OverflowPanelStrip::RemovePanel(Panel* panel) {
+  DCHECK_EQ(this, panel->panel_strip());
   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 +138,6 @@ bool OverflowPanelStrip::RemovePanel(Panel* panel) {
     overflow_indicator_.reset();
   else
     UpdateOverflowIndicatorCount();

[Andrei, 2012/03/01 00:08:50]

Same comment about SetPanelStrip() as for the docked strip

-
-  return true;
 }
 
 void OverflowPanelStrip::CloseAll() {
@@ -163,9 +163,8 @@ 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_->ChangePanelLayout(panel, PanelStrip::DOCKED);

[Andrei, 2012/03/01 00:08:50]

Ideally making sure a panel CAN be activated before calling this should be the
job of the caller. 
I'll put it this way: changing panel layout for a panel is a system-wide side
effect. Are the callers always prepared and aware of the fact that, by calling
ActivatePanel(), they are making a change that reaches far beyond this panel?

Of course I am not sure how costly it would be to change :)

[jennb, 2012/03/01 00:30:58]

For this activation path, the panel can always be activated. This is how a
minimized panel gets restored to expanded mode, or an overflow panel gets moved
back to the dock strip. One usage of this is when extensions want to give focus
to a panel.

+  panel->panel_strip()->ActivatePanel(panel);
 }
 
 void OverflowPanelStrip::MinimizePanel(Panel* panel) {
@@ -175,9 +174,8 @@ 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_->ChangePanelLayout(panel, PanelStrip::DOCKED);

[Andrei, 2012/03/01 00:08:50]

Same as above.

[jennb, 2012/03/01 00:30:58]

Ditto above; this is always allowed.

+  panel->panel_strip()->RestorePanel(panel);
 }
 
 bool OverflowPanelStrip::CanShowPanelAsActive(const Panel* panel) const {