Update to Chromium version 86.0.4240.0 (#800218)

- CefURLRequest::Create is no longer supported in the renderer process
  (see https://crbug.com/891872). Use CefFrame::CreateURLRequest instead.
- Mac platform definitions have been changed from `MACOSX` to `MAC`
  (see https://crbug.com/1105907) and related CMake macro names have
  been updated. The old `OS_MACOSX` define is still set in code and CMake
  for backwards compatibility.
- Linux ARM build is currently broken (see https://crbug.com/1123214).

tests/ceftests/urlrequest_unittest.cc

@@ -2362,6 +2362,11 @@ class RequestTestRunner : public base::RefCountedThreadSafe<RequestTestRunner> {
 
   // Send a request. |complete_callback| will be executed on request completion.
   void SendRequest(const test_request::RequestDoneCallback& done_callback) {
+    if (!is_browser_process_) {
+      // Render process requests must use CefFrame::CreateURLRequest.
+      EXPECT_TRUE(use_frame_method_);
+    }
+
     test_request::SendConfig config;
 
     if (settings_.redirect_request)
@@ -3210,9 +3215,8 @@ bool IsTestSupported(RequestTestMode test_mode,
                      bool test_in_browser,
                      bool test_server_backend,
                      bool test_frame_method) {
-  if (!test_in_browser && !test_server_backend && !test_frame_method) {
-    // Requests from the render process can only reach non-server backends when
-    // using the CefFrame::CreateURLRequest method.
+  if (!test_in_browser && !test_frame_method) {
+    // Render process requests must use CefFrame::CreateURLRequest.
     return false;
   }