Update to Chromium revision 6e53600d (#386251)

- Remove |accept_lang| parameter from CefJSDialogHandler::OnJSDialog
  and CefFormatUrlForSecurityDisplay (see https://crbug.com/336973#c36).
- Remove remaining NPAPI-related code including functions from
  cef_web_plugin.h (see https://crbug.com/493212#c55).
- Mac: 10.7+ deployment target is now required for client applications.
- Mac: Remove CefBrowserHost::SetWindowVisibility (issue #1375). No
  replacement is required for windowed rendering. Use WasHidden for
  off-screen rendering.
- Windows: Visual Studio 2015 Update 2 is now required when building
  CEF/Chromium.

patch/patches/ime_1610.patch

@@ -1,8 +1,8 @@
 diff --git input_method_win.cc input_method_win.cc
-index 9b04a8d..f0578e7 100644
+index 47160e5..1de804e 100644
 --- input_method_win.cc
 +++ input_method_win.cc
-@@ -618,8 +618,9 @@ bool InputMethodWin::IsWindowFocused(const TextInputClient* client) const {
+@@ -629,8 +629,9 @@ bool InputMethodWin::IsWindowFocused(const TextInputClient* client) const {
    // receiving keyboard input as long as it is an active window. This works well
    // even when the |attached_window_handle| becomes active but has not received
    // WM_FOCUS yet.