Update to Chromium revision 0bfd25d4 (#381305)

- Delete include/cef_runnable.h (issue #1336).
- Build the cef_unittests target using all Chromium headers. Add a
  USING_CHROMIUM_INCLUDES define and libcef_dll_wrapper_unittests
  target to support this. This change avoids compile errors due to
  the divergence of CEF and Chromium base/ header implementations.
  The libcef_dll_wrapper sources must now compile successfully with
  both CEF and Chromium base/ headers (issue #1632).
- The onbeforeunload message specified via JavaScript is no longer
  passed to the client (see http://crbug.com/587940).

libcef/browser/browser_context.cc

@@ -36,6 +36,8 @@ CefBrowserContext::~CefBrowserContext() {
 }
 
 void CefBrowserContext::Initialize() {
+  content::BrowserContext::Initialize(this, GetPath());
+
   const bool extensions_enabled = extensions::ExtensionsEnabled();
   if (extensions_enabled) {
     // Create the custom ExtensionSystem first because other KeyedServices