Desktop: Isolate CEF-rendered UI into separate crate and process (#4321)

* Extract CEF rendered UI into a separate process and crate

* Review

* Review

* Review

* Review

* Remove necessary workarounds

* Block on frame copy ack

* Crop and resample frames correctly

* Skip blank frames

* Fix deps

* Fix fmt

* Fix clippy warning

* Review

* Fix todo

desktop/ui/src/internal/browser_process_handler.rs

@@ -0,0 +1,45 @@
+use cef::rc::{Rc, RcImpl};
+use cef::sys::{_cef_browser_process_handler_t, cef_base_ref_counted_t, cef_browser_process_handler_t};
+use cef::{CefString, ImplBrowserProcessHandler, WrapBrowserProcessHandler};
+
+pub(crate) struct BrowserProcessHandlerImpl {
+	object: *mut RcImpl<cef_browser_process_handler_t, Self>,
+}
+impl BrowserProcessHandlerImpl {
+	pub(crate) fn new() -> Self {
+		Self { object: std::ptr::null_mut() }
+	}
+}
+
+impl ImplBrowserProcessHandler for BrowserProcessHandlerImpl {
+	fn on_already_running_app_relaunch(&self, _command_line: Option<&mut cef::CommandLine>, _current_directory: Option<&CefString>) -> std::ffi::c_int {
+		1 // Return 1 to prevent default behavior of opening a empty browser window
+	}
+
+	fn get_raw(&self) -> *mut _cef_browser_process_handler_t {
+		self.object.cast()
+	}
+}
+
+impl Clone for BrowserProcessHandlerImpl {
+	fn clone(&self) -> Self {
+		unsafe {
+			let rc_impl = &mut *self.object;
+			rc_impl.interface.add_ref();
+		}
+		Self { object: self.object }
+	}
+}
+impl Rc for BrowserProcessHandlerImpl {
+	fn as_base(&self) -> &cef_base_ref_counted_t {
+		unsafe {
+			let base = &*self.object;
+			std::mem::transmute(&base.cef_object)
+		}
+	}
+}
+impl WrapBrowserProcessHandler for BrowserProcessHandlerImpl {
+	fn wrap_rc(&mut self, object: *mut RcImpl<_cef_browser_process_handler_t, Self>) {
+		self.object = object;
+	}
+}