Only allow to lock the mouse when the tab is in fullscreen mode.

content/browser/renderer_host/render_widget_host_view_win.cc

 // Copyright (c) 2011 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.
 
 // Need a few defines from Win 7 headers for WM_GESTURE and
 // ChangeWindowMessageFilterEx.
 // TODO(jschuh): See crbug.com/92941 for longterm fix.
 #include <windows.h>
 #if(WINVER < 0x0601)
 typedef struct tagCHANGEFILTERSTRUCT {
@@ skipping 1289 matching lines @@
 LRESULT RenderWidgetHostViewWin::OnKeyEvent(UINT message, WPARAM wparam,
                                             LPARAM lparam, BOOL& handled) {
   handled = TRUE;
 
   // Force fullscreen windows to close on Escape.
   if ((message == WM_KEYDOWN || message == WM_KEYUP) && wparam == VK_ESCAPE) {
     if (mouse_locked_)
       UnlockMouse();
     if (is_fullscreen_)
       SendMessage(WM_CANCELMODE);
-   return 0;
+    return 0;
   }
 
   // If we are a pop-up, forward tab related messages to our parent HWND, so
   // that we are dismissed appropriately and so that the focus advance in our
   // parent.
   // TODO(jcampan): http://b/issue?id=1192881 Could be abstracted in the
   //                FocusManager.
   if (close_on_deactivate_ &&
       (((message == WM_KEYDOWN || message == WM_KEYUP) && (wparam == VK_TAB)) ||
         (message == WM_CHAR && wparam == L'\t'))) {
@@ skipping 630 matching lines @@
   if (message == WM_MOUSEMOVE) {
     CPoint center = GetClientCenter();
     // Ignore WM_MOUSEMOVE messages generated by MoveCursorToCenter().
     if (LOWORD(lparam) == center.x && HIWORD(lparam) == center.y)
       return;
   }
 
   ForwardMouseEventToRenderer(message, wparam, lparam);
 }