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.

libcef/common/crash_reporter_client.h

@@ -37,6 +37,8 @@ class CefCrashReporterClient : public crash_reporter::CrashReporterClient {
   // |crash_dir| was set.
   bool GetCrashDumpLocation(base::FilePath* crash_dir) override;
 
+  bool EnableBreakpadForProcess(const std::string& process_type) override;
+
 private:
   DISALLOW_COPY_AND_ASSIGN(CefCrashReporterClient);
 };