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..8364bf9c6b0f6dd815086777da0ca099ed635f06 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"
@@ -221,9 +224,98 @@
 #endif  // defined(USE_AURA)
 
 using content::BrowserThread;
+using content::WebContents;
+using content::WebContentsObserver;
 
 namespace {
 
+// The basis for when tasks posted via PostAfterStartupTasks begin running.
+using StartupCompleteFlag = base::CancellationFlag;
+base::LazyInstance<StartupCompleteFlag>::Leaky g_startup_complete_flag;
+
+void SetBrowserStartupIsComplete() {
+  g_startup_complete_flag.Get().Set();
+}
+
+// Observes the first page load and set the startup complete flag accordingly.
+class StartupObserver : public WebContentsObserver {

[jam, 2015/03/23 23:19:44]

nit: this would be much smaller lines if the methods were inlined..

[michaeln, 2015/03/24 23:01:11]

Done.

+ public:
+  StartupObserver() : weak_factory_(this) {}
+  ~StartupObserver() override {}
+
+  void Start();
+
+ private:
+  void OnStartupComplete();
+  void OnFailsafeTimeout();
+
+  // 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;
+
+  base::WeakPtrFactory<StartupObserver> weak_factory_;
+};

[cmumford, 2015/03/23 23:57:20]

Not sure: Is DISALLOW_COPY_AND_ASSIGN required for local *.cc classes?

[michaeln, 2015/03/24 23:01:12]

Done.

+
+void StartupObserver::Start() {
+  // Signal completion quickly when there is no first page to load.
+  int kShortDelaySecs = 3;

[cmumford, 2015/03/23 23:57:19]

const int kShortDelaySecs = 3;

[michaeln, 2015/03/24 23:01:11]

Done.

+  base::TimeDelta delay = base::TimeDelta::FromSeconds(kShortDelaySecs);
+
+#if !defined(OS_ANDROID)

[michaeln, 2015/03/23 20:24:23]

FUD: Initially mimic'ing chrome_browser_main_extra_parts_metrics.cc which avoids
monitoring the first page load on android, although i'm not sure why it does.

+  WebContents* contents = nullptr;
+  for (chrome::BrowserIterator iter; !iter.done(); iter.Next()) {
+    contents = (*iter)->tab_strip_model()->GetActiveWebContents();
+    if (contents)
+      break;
+  }
+
+  if (contents) {
+    // Give the page time to finish loading.
+    const int kLongerDelayMins = 3;
+    Observe(contents);
+    delay = base::TimeDelta::FromMinutes(kLongerDelayMins);
+  }
+#endif  // !defined(OS_ANDROID)
+
+  BrowserThread::PostDelayedTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&StartupObserver::OnFailsafeTimeout,
+                 weak_factory_.GetWeakPtr()),
+      delay);
+}
+
+void StartupObserver::OnStartupComplete() {
+  SetBrowserStartupIsComplete();
+  delete this;
+}
+
+void StartupObserver::OnFailsafeTimeout() {
+  OnStartupComplete();
+}
+
+void StartupObserver::DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                                    const GURL& validated_url) {
+  if (web_contents()->GetMainFrame() == render_frame_host)

[cmumford, 2015/03/23 23:57:19]

The rest of Chrome does if (!render_frame_host->GetParent()). Not sure if
there's a difference?

[michaeln, 2015/03/24 23:01:11]

thnx, done

+    OnStartupComplete();
+}
+
+void StartupObserver::DidFailLoad(content::RenderFrameHost* render_frame_host,
+                                  const GURL& validated_url,
+                                  int error_code,
+                                  const base::string16& error_description) {
+  if (web_contents()->GetMainFrame() == render_frame_host)
+    OnStartupComplete();
+}
+
+void StartupObserver::WebContentsDestroyed() {
+  OnStartupComplete();
+}
+
 // This function provides some ways to test crash and assertion handling
 // behavior of the program.
 void HandleTestParameters(const base::CommandLine& command_line) {
@@ -588,6 +680,9 @@ 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 +1204,9 @@ void ChromeBrowserMainParts::PostBrowserStart() {
       base::Bind(&WebRtcLogUtil::DeleteOldWebRtcLogFilesForAllProfiles),
       base::TimeDelta::FromMinutes(1));
 #endif  // defined(ENABLE_WEBRTC)
+
+  // The observer is self-deleting.
+  (new StartupObserver)->Start();
 }
 
 int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
@@ -1735,3 +1833,7 @@ void ChromeBrowserMainParts::PostDestroyThreads() {
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }
+
+bool IsBrowserStartupComplete() {
+  return g_startup_complete_flag.Get().IsSet();
+}