Update to Chromium version 82.0.4085.0 (#749737)

- Building on macOS now requires the 10.15 SDK. Xcode 11.3 is recommended as
  Xcode 11.4 is not currently supported (see https://crbug.com/1065146).
- Jumbo build configuration is no longer supported.

Chromium is skipping the M82 release and consequently no CEF 4085 branch will
be created. For details on the Chromium decision see
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/Vn7uzglqLz0/JItlSrZxBAAJ

libcef/browser/chrome_profile_stub.cc

@@ -5,9 +5,35 @@
 
 #include "libcef/browser/chrome_profile_stub.h"
 
+#include "components/variations/variations_client.h"
+#include "components/variations/variations_http_header_provider.h"
 #include "content/public/browser/resource_context.h"
 #include "net/url_request/url_request_context.h"
 
+namespace {
+
+class CefVariationsClient : public variations::VariationsClient {
+ public:
+  explicit CefVariationsClient(content::BrowserContext* browser_context)
+      : browser_context_(browser_context) {}
+
+  ~CefVariationsClient() override = default;
+
+  bool IsIncognito() const override {
+    return browser_context_->IsOffTheRecord();
+  }
+
+  std::string GetVariationsHeader() const override {
+    return variations::VariationsHttpHeaderProvider::GetInstance()
+        ->GetClientDataHeader(false /* is_signed_in */);
+  }
+
+ private:
+  content::BrowserContext* browser_context_;
+};
+
+}  // namespace
+
 ChromeProfileStub::ChromeProfileStub() {}
 
 ChromeProfileStub::~ChromeProfileStub() {}
@@ -20,6 +46,12 @@ bool ChromeProfileStub::IsOffTheRecord() const {
   return false;
 }
 
+variations::VariationsClient* ChromeProfileStub::GetVariationsClient() {
+  if (!variations_client_)
+    variations_client_ = std::make_unique<CefVariationsClient>(this);
+  return variations_client_.get();
+}
+
 scoped_refptr<base::SequencedTaskRunner> ChromeProfileStub::GetIOTaskRunner() {
   NOTREACHED();
   return scoped_refptr<base::SequencedTaskRunner>();