Implement a poor man's PostAfterStartupTask() function.

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc

Index: chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc
diff --git a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc
index 4eca8affbe670aa975dd0cff50dc0c88cf67b553..4f6f2f3344a1821bdadb94ccc60931441ebf0c82 100644
--- a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc
+++ b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc
@@ -265,6 +265,8 @@ void ChromeBrowserMainExtraPartsMetrics::PostBrowserStart() {
   first_web_contents_profiler_ =
       FirstWebContentsProfiler::CreateProfilerForFirstWebContents(this).Pass();
 #endif  // !defined(OS_ANDROID)
+  if (!first_web_contents_profiler_)
+    chrome::SetBrowserStartupIsComplete();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayAdded(
@@ -284,6 +286,10 @@ void ChromeBrowserMainExtraPartsMetrics::OnDisplayMetricsChanged(
 
 void ChromeBrowserMainExtraPartsMetrics::ProfilerFinishedCollectingMetrics() {
   first_web_contents_profiler_.reset();
+
+  // TODO(michaeln): Revisit this in light of session restore, for now
+  // claim complete after the first page loads.
+  chrome::SetBrowserStartupIsComplete();

[gab, 2015/03/10 15:00:32]

Doesn't feel like ExtraPartsMetrics is the right place for this as it doesn't
have to do with metrics.

[michaeln, 2015/03/10 19:46:26]

Ditto any guidance.

I picked this location because this class and the FirstWebContentsProfiler are
responsible for the Startup.FirstWebContents.MainFrameLoad stat. That's exactly
what i'd like to consider 'isStartedUp' for now. These classes are also
responsible for how that stat is different on android (it's not logged there),
so its more clear why/what is different about the the startup compeltion flag
for android too.

[gab, 2015/03/10 19:55:27]

Then perhaps put it directly in FirstWebContentsProfiler besides the metric
logging? Makes it feel like that's repurposing FirstWebContentsProfiler a bit
beyond strictly "profiling", but that's not too bad IMO (we can rename the class
later if we care).

[michaeln, 2015/03/20 00:21:27]

I put it directly into ChromeBrowserMainParts, nothing extra needed.

 }
 
 void ChromeBrowserMainExtraPartsMetrics::EmitDisplaysChangedMetric() {