Implement a poor man's PostAfterStartupTask() function.

chrome/browser/chrome_content_browser_client.h

Index: chrome/browser/chrome_content_browser_client.h
diff --git a/chrome/browser/chrome_content_browser_client.h b/chrome/browser/chrome_content_browser_client.h
index 8e28784a60e6e390bf5002f8507c4345e7bcd7e3..b76d5b6d09a86029f70fc3f9839d6005943c3608 100644
--- a/chrome/browser/chrome_content_browser_client.h
+++ b/chrome/browser/chrome_content_browser_client.h
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 
+#include <deque>
 #include <set>
 #include <string>
 #include <utility>
@@ -50,6 +51,9 @@ class ChromeContentBrowserClient : public content::ContentBrowserClient {
 
   content::BrowserMainParts* CreateBrowserMainParts(
       const content::MainFunctionParams& parameters) override;
+  void PostAfterStartupTask(const tracked_objects::Location& from_here,
+                            const scoped_refptr<base::TaskRunner>& task_runner,
+                            const base::Closure& task) override;
   std::string GetStoragePartitionIdForSite(
       content::BrowserContext* browser_context,
       const GURL& site) override;
@@ -266,9 +270,8 @@ class ChromeContentBrowserClient : public content::ContentBrowserClient {
       content::FileDescriptorInfo* mappings) override;
 #endif
 #if defined(OS_WIN)
-  virtual const wchar_t* GetResourceDllName() override;
-  virtual void PreSpawnRenderer(sandbox::TargetPolicy* policy,
-                                bool* success) override;
+  const wchar_t* GetResourceDllName() override;
+  void PreSpawnRenderer(sandbox::TargetPolicy* policy, bool* success) override;
 #endif
   bool CheckMediaAccessPermission(content::BrowserContext* browser_context,
                                   const GURL& security_origin,
@@ -284,6 +287,8 @@ class ChromeContentBrowserClient : public content::ContentBrowserClient {
  private:
   friend class DisableWebRtcEncryptionFlagTest;
 
+  void OnAfterStartupTasksTimer();
+
 #if defined(ENABLE_WEBRTC)
   // Copies disable WebRTC encryption switch depending on the channel.
   static void MaybeCopyDisableWebRtcEncryptionSwitch(
@@ -328,6 +333,9 @@ class ChromeContentBrowserClient : public content::ContentBrowserClient {
   base::ScopedFD v8_snapshot_fd_;
 #endif  // OS_POSIX && !OS_MACOSX
 
+  base::WeakPtr<ChromeContentBrowserClient> weak_this_;
+  std::deque<base::Callback<bool(void)>> after_startup_tasks_;
+
   // Vector of additional ChromeContentBrowserClientParts.
   // Parts are deleted in the reverse order they are added.
   std::vector<ChromeContentBrowserClientParts*> extra_parts_;