Update to Chromium version 85.0.4183.0 (#782793)

- Windows: 10.0.19041 SDK is now required.
- macOS: 10.15.1 SDK (at least Xcode 11.2) is now required.
- Remove CefMediaSource::IsValid and CefMediaSink::IsValid which would
  always return true.

patch/patches/chrome_browser_net_export.patch

@@ -1,5 +1,5 @@
 diff --git chrome/browser/ui/BUILD.gn chrome/browser/ui/BUILD.gn
-index 284154368652..cdd775136329 100644
+index 7f8d13d8c4c2..ab5688900991 100644
 --- chrome/browser/ui/BUILD.gn
 +++ chrome/browser/ui/BUILD.gn
 @@ -9,6 +9,7 @@ import("//build/config/crypto.gni")
@@ -10,7 +10,7 @@ index 284154368652..cdd775136329 100644
  import("//chrome/browser/buildflags.gni")
  import("//chrome/common/features.gni")
  import("//chromeos/assistant/assistant.gni")
-@@ -362,6 +363,10 @@ static_library("ui") {
+@@ -335,6 +336,10 @@ static_library("ui") {
      "//build/config/compiler:wexit_time_destructors",
    ]
  
@@ -21,7 +21,7 @@ index 284154368652..cdd775136329 100644
    # Since browser and browser_ui actually depend on each other,
    # we must omit the dependency from browser_ui to browser.
    # However, this means browser_ui and browser should more or less
-@@ -383,6 +388,7 @@ static_library("ui") {
+@@ -356,6 +361,7 @@ static_library("ui") {
      "//base/allocator:buildflags",
      "//build:branding_buildflags",
      "//cc/paint",
@@ -29,7 +29,7 @@ index 284154368652..cdd775136329 100644
      "//chrome:extra_resources",
      "//chrome:resources",
      "//chrome:strings",
-@@ -1489,6 +1495,7 @@ static_library("ui") {
+@@ -1473,6 +1479,7 @@ static_library("ui") {
        "//components/keep_alive_registry",
        "//components/network_session_configurator/common",
        "//components/page_load_metrics/browser",