gtk: Fix the case where a user quickly moves the mouse away from a dragged tab

causing gtk to stop generating motion-notify-event signals.  In this case,
a call to gtk_grab_add lets gtk clean up the drag for us.

BUG=16509
TEST=Quickly move the mouse away from a dragged tab (up and left works best).
The drag will end and a new window will open.  The dragged tab window should
not still exist.
Review URL: http://codereview.chromium.org/159290

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21440 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 33 insertions, 3 deletions

diff --git a/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.cc b/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.cc
index 4625902..0052f01 100644
--- a/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.cc
+++ b/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/gtk/tabs/dragged_tab_controller_gtk.h"
 
+#include <algorithm>
+
 #include "chrome/browser/browser.h"
 #include "chrome/browser/gtk/browser_window_gtk.h"
 #include "chrome/browser/gtk/tabs/dragged_tab_gtk.h"
@@ -100,10 +102,16 @@ TabGtk* DraggedTabControllerGtk::GetDragSourceTabForContents(
   return NULL;
 }
 
-bool DraggedTabControllerGtk::IsDragSourceTab(TabGtk* tab) const {
+bool DraggedTabControllerGtk::IsDragSourceTab(const TabGtk* tab) const {
   return source_tab_ == tab;
 }
 
+bool DraggedTabControllerGtk::IsTabDetached(const TabGtk* tab) const {
+  if (!IsDragSourceTab(tab))
+    return false;
+  return (attached_tabstrip_ == NULL);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DraggedTabControllerGtk, TabContentsDelegate implementation:
 
diff --git a/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.h b/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.h
index 5b1b66b..1b4b1ee 100644
--- a/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.h
+++ b/chrome/browser/gtk/tabs/dragged_tab_controller_gtk.h
@@ -48,7 +48,10 @@ class DraggedTabControllerGtk : public NotificationObserver,
   TabGtk* GetDragSourceTabForContents(TabContents* contents) const;
 
   // Returns true if the specified tab matches the tab being dragged.
-  bool IsDragSourceTab(TabGtk* tab) const;
+  bool IsDragSourceTab(const TabGtk* tab) const;
+
+  // Returns true if the specified tab is detached.
+  bool IsTabDetached(const TabGtk* tab) const;
 
  private:
   // Enumeration of the ways a drag session can end.
diff --git a/chrome/browser/gtk/tabs/tab_gtk.cc b/chrome/browser/gtk/tabs/tab_gtk.cc
index 8394bc4..90241100 100644
--- a/chrome/browser/gtk/tabs/tab_gtk.cc
+++ b/chrome/browser/gtk/tabs/tab_gtk.cc
@@ -248,6 +248,15 @@ void TabGtk::DidProcessEvent(GdkEvent* event) {
     case GDK_MOTION_NOTIFY:
       delegate_->ContinueDrag(NULL);
       break;
+    case GDK_GRAB_BROKEN:
+      // If the user drags the mouse away from the dragged tab before the widget
+      // is created, gtk loses the grab used for the drag and we're stuck in a
+      // limbo where the drag is still active, but we don't get any
+      // motion-notify-event signals.  Adding the grab back doesn't keep the
+      // drag alive, but it does get us out of this bind by finishing the drag.
+      if (delegate_->IsTabDetached(this))
+        gtk_grab_add(widget());
+      break;
     default:
       break;
   }
diff --git a/chrome/browser/gtk/tabs/tab_gtk.h b/chrome/browser/gtk/tabs/tab_gtk.h
index 384f7f6..4d1f704f 100644
--- a/chrome/browser/gtk/tabs/tab_gtk.h
+++ b/chrome/browser/gtk/tabs/tab_gtk.h
@@ -28,6 +28,9 @@ class TabGtk : public TabRendererGtk,
     // Returns true if the specified Tab is selected.
     virtual bool IsTabSelected(const TabGtk* tab) const = 0;
 
+    // Returns true if the specified Tab is detached.
+    virtual bool IsTabDetached(const TabGtk* tab) const = 0;
+
     // Selects the specified Tab.
     virtual void SelectTab(TabGtk* tab) = 0;
 
@@ -72,7 +75,7 @@ class TabGtk : public TabRendererGtk,
     virtual ThemeProvider* GetThemeProvider() = 0;
   };
 
-  TabGtk(TabDelegate* delegate);
+  explicit TabGtk(TabDelegate* delegate);
   virtual ~TabGtk();
 
   // Access the delegate.
diff --git a/chrome/browser/gtk/tabs/tab_strip_gtk.cc b/chrome/browser/gtk/tabs/tab_strip_gtk.cc
index e8bc85e..85031ff 100644
--- a/chrome/browser/gtk/tabs/tab_strip_gtk.cc
+++ b/chrome/browser/gtk/tabs/tab_strip_gtk.cc
@@ -994,6 +994,12 @@ bool TabStripGtk::IsTabSelected(const TabGtk* tab) const {
   return GetIndexOfTab(tab) == model_->selected_index();
 }
 
+bool TabStripGtk::IsTabDetached(const TabGtk* tab) const {
+  if (drag_controller_.get())
+    return drag_controller_->IsTabDetached(tab);
+  return false;
+}
+
 void TabStripGtk::GetCurrentTabWidths(double* unselected_width,
                                       double* selected_width) const {
   *unselected_width = current_unselected_width_;
diff --git a/chrome/browser/gtk/tabs/tab_strip_gtk.h b/chrome/browser/gtk/tabs/tab_strip_gtk.h
index 5890e4a..fb11f50 100644
--- a/chrome/browser/gtk/tabs/tab_strip_gtk.h
+++ b/chrome/browser/gtk/tabs/tab_strip_gtk.h
@@ -106,6 +106,7 @@ class TabStripGtk : public TabStripModelObserver,
 
   // TabGtk::TabDelegate implementation:
   virtual bool IsTabSelected(const TabGtk* tab) const;
+  virtual bool IsTabDetached(const TabGtk* tab) const;
   virtual void SelectTab(TabGtk* tab);
   virtual void CloseTab(TabGtk* tab);
   virtual bool IsCommandEnabledForTab(