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

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

 // Copyright 2013 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/ui/views/toolbar/toolbar_button.h"
 
 #include "base/bind.h"
 #include "chrome/browser/ui/views/location_bar/location_bar_view.h"
 #include "grit/theme_resources.h"
 #include "grit/ui_strings.h"
@@ skipping 159 matching lines @@
   int left_bound = GetSystemMetrics(SM_XVIRTUALSCREEN);
 #elif defined(OS_CHROMEOS)
   // A window won't overlap between displays on ChromeOS.
   // Use the left bound of the display on which
   // the menu button exists.
   gfx::NativeView view = GetWidget()->GetNativeView();
   gfx::Display display = gfx::Screen::GetScreenFor(
       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);
 
   // Make the button look depressed while the menu is open.
   SetState(STATE_PRESSED);
 
   menu_showing_ = true;
 
   // Create and run menu.  Display an empty menu if model is NULL.
@@ skipping 27 matching lines @@
 
   // Need to explicitly clear mouse handler so that events get sent
   // properly after the menu finishes running. If we don't do this, then
   // the first click to other parts of the UI is eaten.
   SetMouseHandler(NULL);
 
   // Set the state back to normal after the drop down menu is closed.
   if (state_ != STATE_DISABLED)
     SetState(STATE_NORMAL);
 }