Refactoring balloon collection and added chromeos's BalloonCollection.

 * Separated BalloonCollection and BalloonCollectionImpl
 * Moved BalloonSpaceChangeListener to BalloonCollection from BalloonCollectionImpl as this listener is used by NotificationUIManager.
 * Added BalloonCollectionImpl for chromeos. (chromeos/notifications/balloon_collectino_impl.{h,cc})
 * Changed NotificationPanel to use ScrollView to show all notifications in the panel.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/660111

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@40460 0039d316-1c4b-4281-b951-d872f2087c98

18 files changed, 417 insertions, 175 deletions

diff --git a/chrome/browser/chromeos/notifications/balloon_collection_impl.cc b/chrome/browser/chromeos/notifications/balloon_collection_impl.cc
new file mode 100644
index 0000000..c941e56
--- /dev/null
+++ b/chrome/browser/chromeos/notifications/balloon_collection_impl.cc
@@ -0,0 +1,124 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/notifications/balloon_collection_impl.h"
+
+#include "base/gfx/rect.h"
+#include "base/gfx/size.h"
+#include "base/logging.h"
+#include "base/stl_util-inl.h"
+#include "chrome/browser/chromeos/notifications/balloon_view.h"
+#include "chrome/browser/chromeos/notifications/notification_panel.h"
+#include "chrome/browser/notifications/balloon.h"
+#include "chrome/browser/notifications/notification.h"
+#include "chrome/browser/window_sizer.h"
+
+namespace {
+
+// Portion of the screen allotted for notifications. When notification balloons
+// extend over this, no new notifications are shown until some are closed.
+const double kPercentBalloonFillFactor = 0.7;
+
+// Allow at least this number of balloons on the screen.
+const int kMinAllowedBalloonCount = 2;
+
+// Margin from the edge of the work area
+const int kVerticalEdgeMargin = 5;
+const int kHorizontalEdgeMargin = 5;
+
+}  // namespace
+
+namespace chromeos {
+
+BalloonCollectionImpl::BalloonCollectionImpl()
+    : panel_(new NotificationPanel()) {
+}
+
+BalloonCollectionImpl::~BalloonCollectionImpl() {
+  STLDeleteElements(&balloons_);
+}
+
+void BalloonCollectionImpl::Add(const Notification& notification,
+                                Profile* profile) {
+  Balloon* new_balloon = MakeBalloon(notification, profile);
+  balloons_.push_back(new_balloon);
+  new_balloon->Show();
+  panel_->Add(new_balloon);
+
+  // There may be no listener in a unit test.
+  if (space_change_listener_)
+    space_change_listener_->OnBalloonSpaceChanged();
+}
+
+bool BalloonCollectionImpl::Remove(const Notification& notification) {
+  Balloons::iterator iter;
+  for (iter = balloons_.begin(); iter != balloons_.end(); ++iter) {
+    if (notification.IsSame((*iter)->notification())) {
+      // Balloon.CloseByScript() will cause OnBalloonClosed() to be called on
+      // this object, which will remove it from the collection and free it.
+      (*iter)->CloseByScript();
+      return true;
+    }
+  }
+  return false;
+}
+
+bool BalloonCollectionImpl::HasSpace() const {
+  return true;
+}
+
+void BalloonCollectionImpl::ResizeBalloon(Balloon* balloon,
+                                          const gfx::Size& size) {
+  // Minimum and maximum size of balloon content.
+  const int kBalloonMinWidth = 300;
+  const int kBalloonMaxWidth = 300;
+  const int kBalloonMinHeight = 24;
+  const int kBalloonMaxHeight = 120;
+
+  // restrict to the min & max sizes
+  gfx::Size real_size(
+      std::max(kBalloonMinWidth,
+               std::min(kBalloonMaxWidth, size.width())),
+      std::max(kBalloonMinHeight,
+               std::min(kBalloonMaxHeight, size.height())));
+  balloon->set_content_size(real_size);
+}
+
+void BalloonCollectionImpl::OnBalloonClosed(Balloon* source) {
+  // We want to free the balloon when finished.
+  scoped_ptr<Balloon> closed(source);
+
+  panel_->Remove(source);
+
+  for (Balloons::iterator it = balloons_.begin(); it != balloons_.end(); ++it) {
+    if (*it == source) {
+      balloons_.erase(it);
+      break;
+    }
+  }
+  // There may be no listener in a unit test.
+  if (space_change_listener_)
+    space_change_listener_->OnBalloonSpaceChanged();
+}
+
+Balloon* BalloonCollectionImpl::MakeBalloon(const Notification& notification,
+                                            Profile* profile) {
+  // TODO(oshima): Move resize logic to Panel.
+  const int kInitialBalloonWidth = 300;
+  const int kInitialBalloonHeight = 60;
+
+  Balloon* balloon = new Balloon(notification, profile, this);
+
+  balloon->set_view(new chromeos::BalloonViewImpl());
+  gfx::Size size(kInitialBalloonWidth, kInitialBalloonHeight);
+  balloon->set_content_size(size);
+  return balloon;
+}
+
+}  // namespace chromeos
+
+// static
+BalloonCollection* BalloonCollection::Create() {
+  return new chromeos::BalloonCollectionImpl();
+}
diff --git a/chrome/browser/chromeos/notifications/balloon_collection_impl.h b/chrome/browser/chromeos/notifications/balloon_collection_impl.h
new file mode 100644
index 0000000..319f9e2
--- /dev/null
+++ b/chrome/browser/chromeos/notifications/balloon_collection_impl.h
@@ -0,0 +1,58 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
+#define CHROME_BROWSER_CHROMEOS_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
+
+#include <deque>
+
+#include "base/basictypes.h"
+#include "base/gfx/point.h"
+#include "base/gfx/rect.h"
+#include "base/scoped_ptr.h"
+#include "chrome/browser/notifications/balloon_collection.h"
+
+namespace chromeos {
+
+class NotificationPanel;
+
+// A balloon collection represents a set of notification balloons being
+// shown in the chromeos notification panel. Unlike other platforms,
+// chromeos shows the all notifications in the notification panel, and
+// this class does not manage the location of balloons.
+class BalloonCollectionImpl : public BalloonCollection {
+ public:
+  BalloonCollectionImpl();
+  virtual ~BalloonCollectionImpl();
+
+  // BalloonCollectionInterface overrides
+  virtual void Add(const Notification& notification,
+                   Profile* profile);
+  virtual bool Remove(const Notification& notification);
+  virtual bool HasSpace() const;
+  virtual void ResizeBalloon(Balloon* balloon, const gfx::Size& size);
+  virtual void OnBalloonClosed(Balloon* source);
+
+ protected:
+  // Creates a new balloon. Overridable by unit tests.  The caller is
+  // responsible for freeing the pointer returned.
+  virtual Balloon* MakeBalloon(const Notification& notification,
+                               Profile* profile);
+
+ private:
+  // The number of balloons being displayed.
+  int count() const { return balloons_.size(); }
+
+  // Queue of active balloons.
+  typedef std::deque<Balloon*> Balloons;
+  Balloons balloons_;
+
+  scoped_ptr<NotificationPanel> panel_;
+
+  DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_NOTIFICATIONS_BALLOON_COLLECTION_H_
diff --git a/chrome/browser/chromeos/notifications/balloon_view.cc b/chrome/browser/chromeos/notifications/balloon_view.cc
index f8b5a04..e541cc3 100644
--- a/chrome/browser/chromeos/notifications/balloon_view.cc
+++ b/chrome/browser/chromeos/notifications/balloon_view.cc
@@ -31,6 +31,8 @@ const int kRevokePermissionCommand = 0;
 
 }  // namespace
 
+namespace chromeos {
+
 BalloonViewImpl::BalloonViewImpl()
     : balloon_(NULL),
       html_contents_(NULL),
@@ -94,12 +96,6 @@ void BalloonViewImpl::Show(Balloon* balloon) {
             balloon_->content_size().width(),
             balloon_->content_size().height() +
             close_button_->GetPreferredSize().height());
-
-  // TODO(oshima): We're not sure if this is the right place to
-  // add & show in the panel. Revisit the deisgn once we have a collection
-  // for chromeos.
-  chromeos::NotificationPanel::Get()->Add(this);
-  chromeos::NotificationPanel::Get()->Show();
   notification_registrar_.Add(this,
     NotificationType::NOTIFY_BALLOON_DISCONNECTED, Source<Balloon>(balloon));
 }
@@ -222,8 +218,7 @@ void BalloonViewImpl::CreateOptionsMenu() {
 
 void BalloonViewImpl::DelayedClose(bool by_user) {
   html_contents_->Shutdown();
-  // Remove html_contents from panel.
-  chromeos::NotificationPanel::Get()->Remove(this);
-
   balloon_->OnClose(by_user);
 }
+
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/notifications/balloon_view.h b/chrome/browser/chromeos/notifications/balloon_view.h
index 5b4fcfa..00ef3b0 100644
--- a/chrome/browser/chromeos/notifications/balloon_view.h
+++ b/chrome/browser/chromeos/notifications/balloon_view.h
@@ -33,6 +33,8 @@ class BalloonViewHost;
 class NotificationDetails;
 class NotificationSource;
 
+namespace chromeos {
+
 // A balloon view is the UI component for a notification panel.
 class BalloonViewImpl : public BalloonView,
                         public views::View,
@@ -107,4 +109,6 @@ class BalloonViewImpl : public BalloonView,
   DISALLOW_COPY_AND_ASSIGN(BalloonViewImpl);
 };
 
+}  // namespace chromeos
+
 #endif  // CHROME_BROWSER_CHROMEOS_NOTIFICATIONS_BALLOON_VIEW_H_
diff --git a/chrome/browser/chromeos/notifications/notification_panel.cc b/chrome/browser/chromeos/notifications/notification_panel.cc
index 46c5b81..5d599ed 100644
--- a/chrome/browser/chromeos/notifications/notification_panel.cc
+++ b/chrome/browser/chromeos/notifications/notification_panel.cc
@@ -9,14 +9,18 @@
 #include "app/gfx/canvas.h"
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
-#include "base/singleton.h"
 #include "chrome/browser/chromeos/notifications/balloon_view.h"
 #include "grit/generated_resources.h"
 #include "views/background.h"
+#include "views/controls/scroll_view.h"
 #include "views/widget/widget_gtk.h"
 
 namespace chromeos {
 
+// Maximum height of the notification panel.
+// TODO(oshima): Get this from system's metrics.
+const int kMaxPanelHeight = 400;
+
 class BalloonContainer : public views::View {
  public:
   explicit BalloonContainer(int margin)
@@ -52,7 +56,8 @@ class BalloonContainer : public views::View {
       height += c->height() + margin_;
       max_width = std::max(max_width, c->width());
     }
-    if (height > 0) height -= margin_;
+    if (height > 0)
+      height -= margin_;
     preferred_size_.set_width(max_width);
     preferred_size_.set_height(height);
     PreferredSizeChanged();
@@ -62,15 +67,12 @@ class BalloonContainer : public views::View {
  private:
   gfx::Size preferred_size_;
   int margin_;
-};
 
-// static
-NotificationPanel* NotificationPanel::Get() {
-  return Singleton<NotificationPanel>::get();
-}
+  DISALLOW_COPY_AND_ASSIGN(BalloonContainer);
+};
 
 NotificationPanel::NotificationPanel()
-    : panel_widget_(NULL) {
+    : balloon_container_(NULL) {
   Init();
 }
 
@@ -79,37 +81,46 @@ NotificationPanel::~NotificationPanel() {
 
 gfx::Rect NotificationPanel::GetPanelBounds() {
   gfx::Size pref_size = balloon_container_->GetPreferredSize();
-  int new_height = pref_size.height();
-  return gfx::Rect(0, 0, pref_size.width(), new_height);
+  int new_height = std::min(pref_size.height(), kMaxPanelHeight);
+  int new_width = pref_size.width();
+  if (new_height != pref_size.height())
+    new_width += scroll_view_->GetScrollBarWidth();
+  return gfx::Rect(0, 0, new_width, new_height);
 }
 
 void NotificationPanel::Init() {
   DCHECK(!panel_widget_.get());
   balloon_container_ = new BalloonContainer(1);
-  balloon_container_->set_parent_owned(false);
   balloon_container_->set_background(
       views::Background::CreateSolidBackground(ResourceBundle::frame_color));
+
+  scroll_view_.reset(new views::ScrollView());
+  scroll_view_->set_parent_owned(false);
+  scroll_view_->SetContents(balloon_container_);
 }
 
-void NotificationPanel::Add(BalloonViewImpl* view) {
+void NotificationPanel::Add(Balloon* balloon) {
+  BalloonViewImpl* view =
+      static_cast<BalloonViewImpl*>(balloon->view());
   balloon_container_->AddChildView(view);
   balloon_container_->UpdateBounds();
-  balloon_container_->Layout();
-  if (panel_widget_.get()) {
+  scroll_view_->Layout();
+  if (panel_widget_.get())
     panel_widget_->SetBounds(GetPanelBounds());
-  }
+  Show();
 }
 
-void NotificationPanel::Remove(BalloonViewImpl* view) {
+void NotificationPanel::Remove(Balloon* balloon) {
+  BalloonViewImpl* view =
+      static_cast<BalloonViewImpl*>(balloon->view());
   balloon_container_->RemoveChildView(view);
   balloon_container_->UpdateBounds();
-  balloon_container_->Layout();
+  scroll_view_->Layout();
   if (panel_widget_.get()) {
-    if (balloon_container_->GetChildViewCount() == 0) {
+    if (balloon_container_->GetChildViewCount() == 0)
       Hide();
-    } else {
+    else
       panel_widget_->SetBounds(GetPanelBounds());
-    }
   }
 }
 
@@ -119,7 +130,7 @@ void NotificationPanel::Show() {
     // when resizing. This needs to be investigated.
     panel_widget_.reset(new views::WidgetGtk(views::WidgetGtk::TYPE_WINDOW));
     panel_widget_->Init(NULL, GetPanelBounds());
-    panel_widget_->SetContentsView(balloon_container_);
+    panel_widget_->SetContentsView(scroll_view_.get());
     panel_controller_.reset(
         new PanelController(this,
                             GTK_WINDOW(panel_widget_->GetNativeView()),
diff --git a/chrome/browser/chromeos/notifications/notification_panel.h b/chrome/browser/chromeos/notifications/notification_panel.h
index 2e6dad5..13062d7 100644
--- a/chrome/browser/chromeos/notifications/notification_panel.h
+++ b/chrome/browser/chromeos/notifications/notification_panel.h
@@ -9,10 +9,13 @@
 
 #include "base/gfx/rect.h"
 #include "base/scoped_ptr.h"
-#include "base/singleton.h"
 #include "chrome/browser/chromeos/frame/panel_controller.h"
 
-class BalloonViewImpl;
+class Balloon;
+
+namespace views {
+class ScrollView;
+}  // namespace views
 
 namespace chromeos {
 
@@ -20,12 +23,11 @@ class BalloonContainer;
 
 class NotificationPanel : PanelController::Delegate {
  public:
-  // Returns the Singleton instance of NotificationPanel.
-  static NotificationPanel* Get();
+  NotificationPanel();
+  virtual ~NotificationPanel();
 
-  // Adds/Removes a ballon view.
-  void Add(BalloonViewImpl* view);
-  void Remove(BalloonViewImpl* view);
+  void Add(Balloon* balloon);
+  void Remove(Balloon* ballon);
 
   // Shows/Hides the Panel.
   void Show();
@@ -37,11 +39,6 @@ class NotificationPanel : PanelController::Delegate {
   virtual void ClosePanel();
 
  private:
-  friend struct DefaultSingletonTraits<NotificationPanel>;
-
-  NotificationPanel();
-  virtual ~NotificationPanel();
-
   void Init();
   // Returns the panel's bounds in the screen's coordinates.
   // The position will be controlled by window manager so
@@ -51,6 +48,9 @@ class NotificationPanel : PanelController::Delegate {
   BalloonContainer* balloon_container_;
   scoped_ptr<views::Widget> panel_widget_;
   scoped_ptr<PanelController> panel_controller_;
+  scoped_ptr<views::ScrollView> scroll_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(NotificationPanel);
 };
 
 }  // namespace chromeos
diff --git a/chrome/browser/notifications/balloon.h b/chrome/browser/notifications/balloon.h
index b0ead85..e5767b3 100644
--- a/chrome/browser/notifications/balloon.h
+++ b/chrome/browser/notifications/balloon.h
@@ -65,6 +65,11 @@ class Balloon {
   // to this object.
   void set_view(BalloonView* balloon_view);
 
+  // Returns the balloon view associated with the balloon.
+  BalloonView* view() {
+    return balloon_view_.get();
+  }
+
   // Returns the viewing size for the balloon (content + frame).
   gfx::Size GetViewSize() const { return balloon_view_->GetSize(); }
 
diff --git a/chrome/browser/notifications/balloon_collection.cc b/chrome/browser/notifications/balloon_collection.cc
index d488228..b8b7e9f 100644
--- a/chrome/browser/notifications/balloon_collection.cc
+++ b/chrome/browser/notifications/balloon_collection.cc
@@ -2,12 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "chrome/browser/notifications/balloon_collection.h"
+#include "chrome/browser/notifications/balloon_collection_impl.h"
 
 #include "base/gfx/rect.h"
+#include "base/gfx/size.h"
 #include "base/logging.h"
 #include "base/stl_util-inl.h"
 #include "chrome/browser/notifications/balloon.h"
+#include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/window_sizer.h"
 
 namespace {
@@ -29,8 +31,7 @@ BalloonCollectionImpl::Layout::Placement
     BalloonCollectionImpl::Layout::placement_ =
         Layout::VERTICALLY_FROM_BOTTOM_RIGHT;
 
-BalloonCollectionImpl::BalloonCollectionImpl()
-    : space_change_listener_(NULL) {
+BalloonCollectionImpl::BalloonCollectionImpl() {
 }
 
 BalloonCollectionImpl::~BalloonCollectionImpl() {
diff --git a/chrome/browser/notifications/balloon_collection.h b/chrome/browser/notifications/balloon_collection.h
index 8bc3132..ff37a12 100644
--- a/chrome/browser/notifications/balloon_collection.h
+++ b/chrome/browser/notifications/balloon_collection.h
@@ -7,19 +7,31 @@
 #ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
 #define CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
 
-#include <deque>
-
-#include "base/gfx/point.h"
-#include "base/gfx/rect.h"
-#include "base/gfx/size.h"
-#include "chrome/browser/notifications/balloon.h"
-#include "chrome/browser/notifications/notification.h"
-
 class Balloon;
+class Notification;
 class Profile;
 
+namespace gfx {
+class Size;
+}  // namespace gfx
+
 class BalloonCollection {
  public:
+  class BalloonSpaceChangeListener {
+   public:
+    virtual ~BalloonSpaceChangeListener() {}
+
+    // Called when there is more or less space for balloons due to
+    // monitor size changes or balloons disappearing.
+    virtual void OnBalloonSpaceChanged() = 0;
+  };
+
+  static BalloonCollection* Create();
+
+  BalloonCollection()
+      : space_change_listener_(NULL) {
+  }
+
   virtual ~BalloonCollection() {}
 
   // Adds a new balloon for the specified notification.
@@ -38,25 +50,6 @@ class BalloonCollection {
 
   // Inform the collection that a balloon was closed.
   virtual void OnBalloonClosed(Balloon* source) = 0;
-};
-
-// A balloon collection represents a set of notification balloons being
-// shown on the screen.  It positions new notifications according to
-// a layout, and monitors for balloons being closed, which it reports
-// up to its parent, the notification UI manager.
-class BalloonCollectionImpl : public BalloonCollection {
- public:
-  class BalloonSpaceChangeListener {
-   public:
-    virtual ~BalloonSpaceChangeListener() {}
-
-    // Called when there is more or less space for balloons due to
-    // monitor size changes or balloons disappearing.
-    virtual void OnBalloonSpaceChanged() = 0;
-  };
-
-  BalloonCollectionImpl();
-  virtual ~BalloonCollectionImpl();
 
   BalloonSpaceChangeListener* space_change_listener() {
     return space_change_listener_;
@@ -65,101 +58,9 @@ class BalloonCollectionImpl : public BalloonCollection {
     space_change_listener_ = listener;
   }
 
-  // BalloonCollectionInterface overrides
-  virtual void Add(const Notification& notification,
-                   Profile* profile);
-  virtual bool Remove(const Notification& notification);
-  virtual bool HasSpace() const;
-  virtual void ResizeBalloon(Balloon* balloon, const gfx::Size& size);
-  virtual void OnBalloonClosed(Balloon* source);
-
  protected:
-  // Calculates layout values for the balloons including
-  // the scaling, the max/min sizes, and the upper left corner of each.
-  class Layout {
-   public:
-    Layout();
-
-    // Refresh the work area and balloon placement.
-    void OnDisplaySettingsChanged();
-
-    // TODO(johnnyg): Scale the size to account for the system font factor.
-    static int min_balloon_width() { return kBalloonMinWidth; }
-    static int max_balloon_width() { return kBalloonMaxWidth; }
-    static int min_balloon_height() { return kBalloonMinHeight; }
-    static int max_balloon_height() { return kBalloonMaxHeight; }
-
-    // Returns both the total space available and the maximum
-    // allowed per balloon.
-    //
-    // The size may be a height or length depending on the way that
-    // balloons are laid out.
-    void GetMaxLinearSize(int* max_balloon_size, int* total_size) const;
-
-    // Refresh the cached values for work area and drawing metrics.
-    // The application should call this method to re-acquire metrics after
-    // any resolution or settings change.
-    // Returns true if and only if a metric changed.
-    bool RefreshSystemMetrics();
-
-    // Returns the origin for the sequence of balloons depending on layout.
-    // Should not be used to place a balloon -- only to call NextPosition().
-    gfx::Point GetLayoutOrigin() const;
-
-    // Compute the position for the next balloon.
-    // Start with *position_iterator = GetLayoutOrigin() and call repeatedly
-    // to get a sequence of positions. Return value is the upper-left coordinate
-    // for each next balloon.
-    gfx::Point NextPosition(const gfx::Size& balloon_size,
-                            gfx::Point* position_iterator) const;
-
-   private:
-    enum Placement {
-      HORIZONTALLY_FROM_BOTTOM_LEFT,
-      HORIZONTALLY_FROM_BOTTOM_RIGHT,
-      VERTICALLY_FROM_TOP_RIGHT,
-      VERTICALLY_FROM_BOTTOM_RIGHT
-    };
-
-    // Layout parameters
-    int VerticalEdgeMargin() const;
-    int HorizontalEdgeMargin() const;
-    int InterBalloonMargin() const;
-
-    // Minimum and maximum size of balloon content.
-    static const int kBalloonMinWidth = 300;
-    static const int kBalloonMaxWidth = 300;
-    static const int kBalloonMinHeight = 24;
-    static const int kBalloonMaxHeight = 120;
-
-    static Placement placement_;
-    gfx::Rect work_area_;
-    DISALLOW_COPY_AND_ASSIGN(Layout);
-  };
-
-  // Creates a new balloon. Overridable by unit tests.  The caller is
-  // responsible for freeing the pointer returned.
-  virtual Balloon* MakeBalloon(const Notification& notification,
-                               Profile* profile);
-
- private:
-  // The number of balloons being displayed.
-  int count() const { return balloons_.size(); }
-
-  // Adjusts the positions of the balloons (e.g., when one is closed).
-  void PositionBalloons(bool is_reposition);
-
   // Non-owned pointer to an object listening for space changes.
   BalloonSpaceChangeListener* space_change_listener_;
-
-  // Queue of active balloons.
-  typedef std::deque<Balloon*> Balloons;
-  Balloons balloons_;
-
-  // The layout parameters for balloons in this collection.
-  Layout layout_;
-
-  DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
diff --git a/chrome/browser/notifications/balloon_collection_impl.h b/chrome/browser/notifications/balloon_collection_impl.h
new file mode 100644
index 0000000..c8eef59
--- /dev/null
+++ b/chrome/browser/notifications/balloon_collection_impl.h
@@ -0,0 +1,120 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Handles the visible notification (or balloons).
+
+#ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
+#define CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
+
+#include <deque>
+
+#include "base/basictypes.h"
+#include "base/gfx/point.h"
+#include "base/gfx/rect.h"
+#include "chrome/browser/notifications/balloon_collection.h"
+
+// A balloon collection represents a set of notification balloons being
+// shown on the screen.  It positions new notifications according to
+// a layout, and monitors for balloons being closed, which it reports
+// up to its parent, the notification UI manager.
+class BalloonCollectionImpl : public BalloonCollection {
+ public:
+  BalloonCollectionImpl();
+  virtual ~BalloonCollectionImpl();
+
+  // BalloonCollectionInterface overrides
+  virtual void Add(const Notification& notification,
+                   Profile* profile);
+  virtual bool Remove(const Notification& notification);
+  virtual bool HasSpace() const;
+  virtual void ResizeBalloon(Balloon* balloon, const gfx::Size& size);
+  virtual void OnBalloonClosed(Balloon* source);
+
+ protected:
+  // Calculates layout values for the balloons including
+  // the scaling, the max/min sizes, and the upper left corner of each.
+  class Layout {
+   public:
+    Layout();
+
+    // Refresh the work area and balloon placement.
+    void OnDisplaySettingsChanged();
+
+    // TODO(johnnyg): Scale the size to account for the system font factor.
+    static int min_balloon_width() { return kBalloonMinWidth; }
+    static int max_balloon_width() { return kBalloonMaxWidth; }
+    static int min_balloon_height() { return kBalloonMinHeight; }
+    static int max_balloon_height() { return kBalloonMaxHeight; }
+
+    // Returns both the total space available and the maximum
+    // allowed per balloon.
+    //
+    // The size may be a height or length depending on the way that
+    // balloons are laid out.
+    void GetMaxLinearSize(int* max_balloon_size, int* total_size) const;
+
+    // Refresh the cached values for work area and drawing metrics.
+    // The application should call this method to re-acquire metrics after
+    // any resolution or settings change.
+    // Returns true if and only if a metric changed.
+    bool RefreshSystemMetrics();
+
+    // Returns the origin for the sequence of balloons depending on layout.
+    // Should not be used to place a balloon -- only to call NextPosition().
+    gfx::Point GetLayoutOrigin() const;
+
+    // Compute the position for the next balloon.
+    // Start with *position_iterator = GetLayoutOrigin() and call repeatedly
+    // to get a sequence of positions. Return value is the upper-left coordinate
+    // for each next balloon.
+    gfx::Point NextPosition(const gfx::Size& balloon_size,
+                            gfx::Point* position_iterator) const;
+
+   private:
+    enum Placement {
+      HORIZONTALLY_FROM_BOTTOM_LEFT,
+      HORIZONTALLY_FROM_BOTTOM_RIGHT,
+      VERTICALLY_FROM_TOP_RIGHT,
+      VERTICALLY_FROM_BOTTOM_RIGHT
+    };
+
+    // Layout parameters
+    int VerticalEdgeMargin() const;
+    int HorizontalEdgeMargin() const;
+    int InterBalloonMargin() const;
+
+    // Minimum and maximum size of balloon content.
+    static const int kBalloonMinWidth = 300;
+    static const int kBalloonMaxWidth = 300;
+    static const int kBalloonMinHeight = 24;
+    static const int kBalloonMaxHeight = 120;
+
+    static Placement placement_;
+    gfx::Rect work_area_;
+    DISALLOW_COPY_AND_ASSIGN(Layout);
+  };
+
+  // Creates a new balloon. Overridable by unit tests.  The caller is
+  // responsible for freeing the pointer returned.
+  virtual Balloon* MakeBalloon(const Notification& notification,
+                               Profile* profile);
+
+ private:
+  // The number of balloons being displayed.
+  int count() const { return balloons_.size(); }
+
+  // Adjusts the positions of the balloons (e.g., when one is closed).
+  void PositionBalloons(bool is_reposition);
+
+  // Queue of active balloons.
+  typedef std::deque<Balloon*> Balloons;
+  Balloons balloons_;
+
+  // The layout parameters for balloons in this collection.
+  Layout layout_;
+
+  DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_IMPL_H_
diff --git a/chrome/browser/notifications/balloon_collection_linux.cc b/chrome/browser/notifications/balloon_collection_linux.cc
index e85ed0c..5d0c2b7 100644
--- a/chrome/browser/notifications/balloon_collection_linux.cc
+++ b/chrome/browser/notifications/balloon_collection_linux.cc
@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "chrome/browser/notifications/balloon_collection.h"
+#include "chrome/browser/notifications/balloon_collection_impl.h"
 
 #include "base/gfx/size.h"
-#include "base/logging.h"
 #include "chrome/browser/notifications/balloon.h"
 #include "chrome/browser/views/notifications/balloon_view.h"
 
@@ -30,3 +29,8 @@ int BalloonCollectionImpl::Layout::HorizontalEdgeMargin() const {
 int BalloonCollectionImpl::Layout::VerticalEdgeMargin() const {
   return 5;
 }
+
+// static
+BalloonCollection* BalloonCollection::Create() {
+  return new BalloonCollectionImpl();
+}
diff --git a/chrome/browser/notifications/balloon_collection_mac.mm b/chrome/browser/notifications/balloon_collection_mac.mm
index f484fd6..f11fc9d 100644
--- a/chrome/browser/notifications/balloon_collection_mac.mm
+++ b/chrome/browser/notifications/balloon_collection_mac.mm
@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "chrome/browser/notifications/balloon_collection.h"
-#include "chrome/browser/cocoa/notifications/balloon_view_bridge.h"
+#include "chrome/browser/notifications/balloon_collection_impl.h"
 
-#include "base/logging.h"
+#include "chrome/browser/cocoa/notifications/balloon_view_bridge.h"
 
 Balloon* BalloonCollectionImpl::MakeBalloon(const Notification& notification,
                                             Profile* profile) {
@@ -27,3 +26,8 @@ int BalloonCollectionImpl::Layout::HorizontalEdgeMargin() const {
 int BalloonCollectionImpl::Layout::VerticalEdgeMargin() const {
   return 18;
 }
+
+// static
+BalloonCollection* BalloonCollection::Create() {
+  return new BalloonCollectionImpl();
+}
diff --git a/chrome/browser/notifications/balloon_collection_win.cc b/chrome/browser/notifications/balloon_collection_win.cc
index b21923e..405ea04 100644
--- a/chrome/browser/notifications/balloon_collection_win.cc
+++ b/chrome/browser/notifications/balloon_collection_win.cc
@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "chrome/browser/notifications/balloon_collection.h"
+#include "chrome/browser/notifications/balloon_collection_impl.h"
 
 #include "base/gfx/rect.h"
-#include "base/logging.h"
 #include "chrome/browser/notifications/balloon.h"
 #include "chrome/browser/views/notifications/balloon_view.h"
 
@@ -29,3 +28,8 @@ int BalloonCollectionImpl::Layout::HorizontalEdgeMargin() const {
 int BalloonCollectionImpl::Layout::VerticalEdgeMargin() const {
   return 5;
 }
+
+// static
+BalloonCollection* BalloonCollection::Create() {
+  return new BalloonCollectionImpl();
+}
diff --git a/chrome/browser/notifications/desktop_notifications_unittest.h b/chrome/browser/notifications/desktop_notifications_unittest.h
index 4297768..927e519 100644
--- a/chrome/browser/notifications/desktop_notifications_unittest.h
+++ b/chrome/browser/notifications/desktop_notifications_unittest.h
@@ -12,7 +12,7 @@
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/notifications/balloon.h"
-#include "chrome/browser/notifications/balloon_collection.h"
+#include "chrome/browser/notifications/balloon_collection_impl.h"
 #include "chrome/browser/notifications/desktop_notification_service.h"
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/notifications/notification_object_proxy.h"
diff --git a/chrome/browser/notifications/notification_ui_manager.cc b/chrome/browser/notifications/notification_ui_manager.cc
index 0330570..e5ae3bd 100644
--- a/chrome/browser/notifications/notification_ui_manager.cc
+++ b/chrome/browser/notifications/notification_ui_manager.cc
@@ -42,7 +42,7 @@ NotificationUIManager::~NotificationUIManager() {
 
 // static
 NotificationUIManager* NotificationUIManager::Create() {
-  BalloonCollectionImpl* balloons = new BalloonCollectionImpl();
+  BalloonCollection* balloons = BalloonCollection::Create();
   NotificationUIManager* instance = new NotificationUIManager();
   instance->Initialize(balloons);
   balloons->set_space_change_listener(instance);
diff --git a/chrome/browser/notifications/notification_ui_manager.h b/chrome/browser/notifications/notification_ui_manager.h
index 9aff1d4..9e2cf18 100644
--- a/chrome/browser/notifications/notification_ui_manager.h
+++ b/chrome/browser/notifications/notification_ui_manager.h
@@ -20,7 +20,7 @@ class SiteInstance;
 // The notification manager manages use of the desktop for notifications.
 // It maintains a queue of pending notifications when space becomes constrained.
 class NotificationUIManager
-    : public BalloonCollectionImpl::BalloonSpaceChangeListener {
+    : public BalloonCollection::BalloonSpaceChangeListener {
  public:
   NotificationUIManager();
   virtual ~NotificationUIManager();
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 1b2c93f..a1352ed 100755
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -294,6 +294,8 @@
         'browser/chrome_plugin_host.h',
         'browser/chrome_thread.cc',
         'browser/chrome_thread.h',
+        'browser/chromeos/notifications/balloon_collection_impl.h',
+        'browser/chromeos/notifications/balloon_collection_impl.cc',
         'browser/chromeos/notifications/balloon_view.h',
         'browser/chromeos/notifications/balloon_view.cc',
         'browser/chromeos/notifications/notification_panel.h',
@@ -1462,6 +1464,7 @@
         'browser/notifications/balloon.h',
         'browser/notifications/balloon_collection.cc',
         'browser/notifications/balloon_collection.h',
+        'browser/notifications/balloon_collection_impl.h',
         'browser/notifications/balloon_collection_win.cc',
         'browser/notifications/balloon_collection_mac.mm',
         'browser/notifications/balloon_collection_linux.cc',
@@ -2802,8 +2805,11 @@
               ],
             }],
             ['OS=="linux" and chromeos==1',{
+              'sources/': [
+                ['exclude', '^browser/notifications/balloon_collection_linux.cc'],
+                ['exclude', '^browser/notifications/balloon_collection_impl.h'],
+              ],
               'dependencies': [
-
                 '../third_party/protobuf2/protobuf.gyp:protobuf_lite',
                 '../third_party/protobuf2/protobuf.gyp:protoc#host',
                 '../third_party/chromeos_login_manager/chromeos_login_manager/chromeos_login_manager.gyp:session',
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 3a004ba..533d779 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -978,6 +978,11 @@
              ['include', 'browser/views/bookmark_context_menu_test.cc$'],
           ],
         }],
+        ['OS=="linux" and chromeos==1', {
+          'sources/': [
+            ['exclude',  'browser/notifications/desktop_notifications_unittest\\.cc$'],
+          ]
+        }],
         ['OS=="mac"', {
            # The test fetches resources which means Mac need the app bundle to
            # exist on disk so it can pull from it.