Implement a poor man's PostAfterStartupTask() function.

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index 1d362a634301b4178ce2a3d3f6b57a56dcf1a639..0881617f6db13664d86d41e507bb011089cb58c8 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -31,6 +31,7 @@
 #include "base/strings/string_split.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/synchronization/cancellation_flag.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
@@ -85,10 +86,12 @@
 #include "chrome/browser/ui/app_list/app_list_service.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_finder.h"
+#include "chrome/browser/ui/browser_iterator.h"
 #include "chrome/browser/ui/host_desktop.h"
 #include "chrome/browser/ui/startup/bad_flags_prompt.h"
 #include "chrome/browser/ui/startup/default_browser_prompt.h"
 #include "chrome/browser/ui/startup/startup_browser_creator.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/uma_browsing_activity_observer.h"
 #include "chrome/browser/ui/webui/chrome_web_ui_controller_factory.h"
 #include "chrome/common/chrome_constants.h"
@@ -224,6 +227,87 @@ using content::BrowserThread;
 
 namespace {
 
+using StartupCompleteFlag = base::CancellationFlag;
+base::LazyInstance<StartupCompleteFlag>::Leaky g_startup_complete_flag;
+
+// Used to monitor the first page load to inform PostAfterStartupTask.
+class StartupObserver : public content::WebContentsObserver {
+ public:
+  static void Start();
+
+ private:
+  static content::WebContents* GetFirstWebContents();
+  static void SetBrowserStartupIsComplete();

[michaeln, 2015/03/20 00:21:28]

i'll probably have to expose SetBrowserStartupIsComplete for testing

+
+  explicit StartupObserver(content::WebContents* web_contents)
+      : content::WebContentsObserver(web_contents) {}
+
+  // WebContentsObserver overrides
+  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                     const GURL& validated_url) override;
+  void DidFailLoad(content::RenderFrameHost* render_frame_host,
+                   const GURL& validated_url,
+                   int error_code,
+                   const base::string16& error_description) override;
+  void WebContentsDestroyed() override;
+};
+
+void StartupObserver::Start() {
+  // Signal completion quickly when there is no first page to load.
+  int kDefaultDelaySecs = 3;
+  base::TimeDelta delay = base::TimeDelta::FromSeconds(kDefaultDelaySecs);
+
+#if !defined(OS_ANDROID)
+  content::WebContents* web_contents = GetFirstWebContents();
+  if (web_contents) {
+    // StartupObserver is self deleting.
+    new StartupObserver(web_contents);
+
+    // In case startup oberver never signals completion.
+    const int kFailsafeDelayMins = 3;
+    delay = base::TimeDelta::FromMinutes(kFailsafeDelayMins);
+  }
+#endif  // !defined(OS_ANDROID)
+
+  BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE,
+                                 base::Bind(&SetBrowserStartupIsComplete),
+                                 delay);
+}
+
+content::WebContents* StartupObserver::GetFirstWebContents() {
+  for (chrome::BrowserIterator iterator; !iterator.done(); iterator.Next()) {
+    Browser* browser = *iterator;
+    content::WebContents* web_contents =
+        browser->tab_strip_model()->GetActiveWebContents();
+    if (web_contents)
+      return web_contents;
+  }
+  return nullptr;
+}
+
+void StartupObserver::SetBrowserStartupIsComplete() {
+  g_startup_complete_flag.Get().Set();
+}
+
+void StartupObserver::DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                                    const GURL& validated_url) {
+  SetBrowserStartupIsComplete();
+  delete this;
+}
+
+void StartupObserver::DidFailLoad(content::RenderFrameHost* render_frame_host,
+                                  const GURL& validated_url,
+                                  int error_code,
+                                  const base::string16& error_description) {
+  SetBrowserStartupIsComplete();
+  delete this;
+}
+
+void StartupObserver::WebContentsDestroyed() {
+  SetBrowserStartupIsComplete();
+  delete this;
+}
+
 // This function provides some ways to test crash and assertion handling
 // behavior of the program.
 void HandleTestParameters(const base::CommandLine& command_line) {
@@ -588,6 +672,9 @@ ChromeBrowserMainParts::ChromeBrowserMainParts(
   // cookies need to go through one of Chrome's URLRequestContexts which have
   // a ChromeNetworkDelegate attached that selectively allows cookies again.
   net::URLRequest::SetDefaultCookiePolicyToBlock();
+
+  // Be sure to allocate the lazy instance on the main thread.
+  g_startup_complete_flag.Get();
 }
 
 ChromeBrowserMainParts::~ChromeBrowserMainParts() {
@@ -1109,6 +1196,7 @@ void ChromeBrowserMainParts::PostBrowserStart() {
       base::Bind(&WebRtcLogUtil::DeleteOldWebRtcLogFilesForAllProfiles),
       base::TimeDelta::FromMinutes(1));
 #endif  // defined(ENABLE_WEBRTC)
+  StartupObserver::Start();
 }
 
 int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
@@ -1735,3 +1823,7 @@ void ChromeBrowserMainParts::PostDestroyThreads() {
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }
+
+bool IsBrowserStartupComplete() {
+  return g_startup_complete_flag.Get().IsSet();
+}