Linux: show tab context menu on mousedown rather than mouse up.

TEST=right click on a tab and see a context menu popup (i.e. no regression). Also, right click, hold, drag, release to select an item.

Review URL: http://codereview.chromium.org/118023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17218 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/gtk/tabs/tab_gtk.cc

@@ -167,6 +167,8 @@ gboolean TabGtk::OnMousePress(GtkWidget* widget, GdkEventButton* event,
     if (just_selected) {
       tab->delegate_->SelectTab(tab);
     }
+  } else if (event->button == 3) {
+    tab->ShowContextMenu();
   }
 
   return TRUE;
@@ -177,8 +179,6 @@ gboolean TabGtk::OnMouseRelease(GtkWidget* widget, GdkEventButton* event,
                                 TabGtk* tab) {
   if (event->button == 2) {
     tab->delegate_->CloseTab(tab);
-  } else if (event->button == 3) {
-    tab->ShowContextMenu();
   }
 
   return TRUE;