linux_aura: Put toolbar dropdown menus on the screen with the cursor.

chrome/browser/ui/views/toolbar/toolbar_button.cc

Index: chrome/browser/ui/views/toolbar/toolbar_button.cc
diff --git a/chrome/browser/ui/views/toolbar/toolbar_button.cc b/chrome/browser/ui/views/toolbar/toolbar_button.cc
index a7cf0c7c2e6a8afc1633ae37b5612a866e574957..2e0e6a4458d744d2d8e03ca1bf2870a16e54b145 100644
--- a/chrome/browser/ui/views/toolbar/toolbar_button.cc
+++ b/chrome/browser/ui/views/toolbar/toolbar_button.cc
@@ -177,8 +177,13 @@ void ToolbarButton::ShowDropDownMenu(ui::MenuSourceType source_type) {
       view)->GetDisplayNearestWindow(view);
   int left_bound = display.bounds().x();
 #else
-  int left_bound = 0;
-  NOTIMPLEMENTED();
+  // The window might be positioned over the edge between two screens. We'll
+  // want to position the dropdown on the screen the mouse cursor is on.
+  gfx::NativeView view = GetWidget()->GetNativeView();
+  gfx::Screen* screen = gfx::Screen::GetScreenFor(view);
+  gfx::Display display = screen->GetDisplayNearestPoint(
+      screen->GetCursorScreenPoint());
+  int left_bound = display.bounds().x();
 #endif
   if (menu_position.x() < left_bound)
     menu_position.set_x(left_bound);