widevine: Use component updater with the Alloy runtime (fixes issue #3149)

Widevine CDM binaries will be downloaded on supported platforms shortly after
application startup. Widevine support will then become available within a few
seconds after successful installation on Windows or after the next application
restart on other platforms. The CDM files will be downloaded to a "WidevineCdm"
directory inside the `CefSettings.user_data_path` directory.

Pass the `--disable-component-update` command-line flag to disable Widevine
download and installation. Pass the `--component-updater=fast-update` command-
line flag to force Widevine download immediately after application startup.

See the related issue for additional usage details.

libcef/browser/alloy/alloy_browser_main.cc

@@ -30,6 +30,7 @@
 #include "chrome/browser/media/router/chrome_media_router_factory.h"
 #include "chrome/browser/net/system_network_context_manager.h"
 #include "chrome/browser/plugins/plugin_finder.h"
+#include "chrome/common/chrome_switches.h"
 #include "components/constrained_window/constrained_window_views.h"
 #include "content/public/browser/gpu_data_manager.h"
 #include "content/public/browser/network_service_instance.h"
@@ -37,6 +38,7 @@
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/constants.h"
 #include "net/base/net_module.h"
+#include "third_party/widevine/cdm/buildflags.h"
 #include "ui/base/resource/resource_bundle.h"
 
 #if defined(USE_AURA) && defined(USE_X11)
@@ -73,6 +75,14 @@
 #include "libcef/browser/printing/print_dialog_linux.h"
 #endif
 
+#if BUILDFLAG(ENABLE_MEDIA_FOUNDATION_WIDEVINE_CDM)
+#include "chrome/browser/component_updater/media_foundation_widevine_cdm_component_installer.h"
+#endif
+
+#if BUILDFLAG(ENABLE_WIDEVINE_CDM_COMPONENT)
+#include "chrome/browser/component_updater/widevine_cdm_component_installer.h"
+#endif
+
 AlloyBrowserMainParts::AlloyBrowserMainParts(
     const content::MainFunctionParams& parameters)
     : BrowserMainParts(), devtools_delegate_(nullptr) {}
@@ -207,6 +217,20 @@ int AlloyBrowserMainParts::PreMainMessageLoopRun() {
 
   scheme::RegisterWebUIControllerFactory();
 
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  if (!command_line->HasSwitch(switches::kDisableComponentUpdate)) {
+    auto* const cus = g_browser_process->component_updater();
+
+#if BUILDFLAG(ENABLE_MEDIA_FOUNDATION_WIDEVINE_CDM)
+    RegisterMediaFoundationWidevineCdmComponent(cus);
+#endif
+
+#if BUILDFLAG(ENABLE_WIDEVINE_CDM_COMPONENT)
+    RegisterWidevineCdmComponent(cus);
+#endif
+  }
+
   return content::RESULT_CODE_NORMAL_EXIT;
 }