Set enable_background_mode=false by default (see issue #2969)

This mode doesn't make sense with CEF, and it was causing strange
shutdown crashes when running with Chrome mode enabled.

BUILD.gn

@@ -812,6 +812,7 @@ static_library("libcef_static") {
     "//chrome:packed_resources",
     "//chrome:resources",
     "//chrome:strings",
+    "//chrome/common:buildflags",
     "//chrome/services/printing:lib",
     "//components/cdm/renderer",
     "//components/certificate_transparency",

libcef/browser/chrome_browser_process_stub.cc

@@ -289,6 +289,7 @@ DownloadRequestLimiter* ChromeBrowserProcessStub::download_request_limiter() {
   return nullptr;
 }
 
+#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
 BackgroundModeManager* ChromeBrowserProcessStub::background_mode_manager() {
   NOTREACHED();
   return nullptr;
@@ -298,6 +299,7 @@ void ChromeBrowserProcessStub::set_background_mode_manager_for_test(
     std::unique_ptr<BackgroundModeManager> manager) {
   NOTREACHED();
 }
+#endif
 
 StatusTray* ChromeBrowserProcessStub::status_tray() {
   NOTREACHED();

libcef/browser/chrome_browser_process_stub.h

@@ -73,9 +73,11 @@ class ChromeBrowserProcessStub : public BrowserProcess {
   void SetApplicationLocale(const std::string& locale) override;
   DownloadStatusUpdater* download_status_updater() override;
   DownloadRequestLimiter* download_request_limiter() override;
+#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
   BackgroundModeManager* background_mode_manager() override;
   void set_background_mode_manager_for_test(
       std::unique_ptr<BackgroundModeManager> manager) override;
+#endif
   StatusTray* status_tray() override;
   safe_browsing::SafeBrowsingService* safe_browsing_service() override;
   subresource_filter::RulesetService* subresource_filter_ruleset_service()

patch/patch.cfg

@@ -512,5 +512,10 @@ patches = [
     # ChromePageInfoClient::GetJavaResourceId.
     # https://bugs.chromium.org/p/chromium/issues/detail?id=1099927
     'name': 'linux_chrome_page_info_1099927',
+  },
+  {
+    # Fix build errors with enable_background_mode=false.
+    # https://bugs.chromium.org/p/chromium/issues/detail?id=1100085
+    'name': 'chrome_browser_background_mode_1100085',
   }
 ]

patch/patches/chrome_browser_background_mode_1100085.patch

@@ -0,0 +1,108 @@
+diff --git chrome/browser/browser_process.h chrome/browser/browser_process.h
+index 6332572ac884..bf555124ce59 100644
+--- chrome/browser/browser_process.h
++++ chrome/browser/browser_process.h
+@@ -197,10 +197,12 @@ class BrowserProcess {
+   virtual DownloadStatusUpdater* download_status_updater() = 0;
+   virtual DownloadRequestLimiter* download_request_limiter() = 0;
+ 
++#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+   // Returns the object that manages background applications.
+   virtual BackgroundModeManager* background_mode_manager() = 0;
+   virtual void set_background_mode_manager_for_test(
+       std::unique_ptr<BackgroundModeManager> manager) = 0;
++#endif
+ 
+   // Returns the StatusTray, which provides an API for displaying status icons
+   // in the system status tray. Returns NULL if status icons are not supported
+diff --git chrome/browser/browser_process_impl.cc chrome/browser/browser_process_impl.cc
+index 13958187a750..0017954a32da 100644
+--- chrome/browser/browser_process_impl.cc
++++ chrome/browser/browser_process_impl.cc
+@@ -963,24 +963,19 @@ DownloadRequestLimiter* BrowserProcessImpl::download_request_limiter() {
+   return download_request_limiter_.get();
+ }
+ 
++#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+ BackgroundModeManager* BrowserProcessImpl::background_mode_manager() {
+   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+-#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+   if (!background_mode_manager_)
+     CreateBackgroundModeManager();
+   return background_mode_manager_.get();
+-#else
+-  NOTIMPLEMENTED();
+-  return NULL;
+-#endif
+ }
+ 
+ void BrowserProcessImpl::set_background_mode_manager_for_test(
+     std::unique_ptr<BackgroundModeManager> manager) {
+-#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+   background_mode_manager_ = std::move(manager);
+-#endif
+ }
++#endif
+ 
+ StatusTray* BrowserProcessImpl::status_tray() {
+   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+diff --git chrome/browser/browser_process_impl.h chrome/browser/browser_process_impl.h
+index 12c76fb96762..60637b2b0044 100644
+--- chrome/browser/browser_process_impl.h
++++ chrome/browser/browser_process_impl.h
+@@ -164,9 +164,11 @@ class BrowserProcessImpl : public BrowserProcess,
+   void SetApplicationLocale(const std::string& actual_locale) override;
+   DownloadStatusUpdater* download_status_updater() override;
+   DownloadRequestLimiter* download_request_limiter() override;
++#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+   BackgroundModeManager* background_mode_manager() override;
+   void set_background_mode_manager_for_test(
+       std::unique_ptr<BackgroundModeManager> manager) override;
++#endif
+   StatusTray* status_tray() override;
+   safe_browsing::SafeBrowsingService* safe_browsing_service() override;
+   subresource_filter::RulesetService* subresource_filter_ruleset_service()
+diff --git chrome/browser/lifetime/browser_close_manager.cc chrome/browser/lifetime/browser_close_manager.cc
+index bc7995a47fbd..28d3658d2885 100644
+--- chrome/browser/lifetime/browser_close_manager.cc
++++ chrome/browser/lifetime/browser_close_manager.cc
+@@ -147,12 +147,14 @@ void BrowserCloseManager::CloseBrowsers() {
+   // exit can restore all browsers open before exiting.
+   ProfileManager::ShutdownSessionServices();
+ #endif
++#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
+   if (!browser_shutdown::IsTryingToQuit()) {
+     BackgroundModeManager* background_mode_manager =
+         g_browser_process->background_mode_manager();
+     if (background_mode_manager)
+       background_mode_manager->SuspendBackgroundMode();
+   }
++#endif
+ 
+   // Make a copy of the BrowserList to simplify the case where we need to
+   // destroy a Browser during the loop.
+diff --git chrome/browser/sessions/session_service.cc chrome/browser/sessions/session_service.cc
+index f5079f6d2189..a43a981d471b 100644
+--- chrome/browser/sessions/session_service.cc
++++ chrome/browser/sessions/session_service.cc
+@@ -942,12 +942,19 @@ void SessionService::MaybeDeleteSessionOnlyData() {
+   if (!profile() || profile()->AsTestingProfile())
+     return;
+ 
++#if BUILDFLAG(ENABLE_BACKGROUND_MODE)
++  const bool background_mode_active =
++      g_browser_process->background_mode_manager()->IsBackgroundModeActive();
++#else
++  const bool background_mode_active = false;
++#endif
++
+   // Clear session data if the last window for a profile has been closed and
+   // closing the last window would normally close Chrome, unless background mode
+   // is active.  Tests don't have a background_mode_manager.
+   if (has_open_trackable_browsers_ ||
+       browser_defaults::kBrowserAliveWithNoWindows ||
+-      g_browser_process->background_mode_manager()->IsBackgroundModeActive()) {
++      background_mode_active) {
+     return;
+   }
+ 

tools/gn_args.py

@@ -215,6 +215,12 @@ def GetRecommendedDefaultArgs():
       # and macOS builds. Currently turned off for CEF because it requires
       # additional setup and is not yet tested. See issue #2956.
       'chrome_pgo_phase': 0,
+
+      # Disable support for background apps, which don't make sense with CEF.
+      # Default is enabled on desktop platforms. This feature was also causing
+      # strange shutdown crashes when using the Chrome runtime with a Debug
+      # component build on Windows.
+      'enable_background_mode': False,
   }
 
   if platform == 'linux':