Use ThreadChecker rather than DCHECK_CURRENTLY_ON.

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index 5219a9f25616d7d31b1c2fa1a90d2e7ccc3e8459..e2ca8732fc559ceb715cd02a99a7d1ed0abfe5be 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -511,6 +511,7 @@ ProfileImpl::ProfileImpl(
 
 void ProfileImpl::DoFinalInit() {
   TRACE_EVENT0("browser", "ProfileImpl::DoFinalInit")
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   PrefService* prefs = GetPrefs();
   pref_change_registrar_.Init(prefs);
   pref_change_registrar_.Add(
@@ -631,6 +632,9 @@ void ProfileImpl::DoFinalInit() {
 
   InitHostZoomMap();
 
+  // Make sure HostContentSettingsMap is created on the UI thread.

[vabr (Chromium), 2014/10/01 11:14:48]

This only really makes sure that HCSM is created on the UI, if we expect HCSM is
actually created here. If that's the case, should there be a
DCHECK(!host_content_settings_map_); just before the GetHostContentSettingsMap()
call?

Alternatively, should we somehow let HCSM check through its new thread_checker_,
that this is the thread it got created on?

If you change something here to accommodate the above, please also change the
OTR profile accordingly.

[vabr (Chromium), 2014/10/01 11:14:48]

Also, should chrome/test/base/testing_profile.cc get a similar call to
GetHostContentSettingsMap() in its Init() or FinishInit()?

[Bernhard Bauer, 2014/10/01 11:41:09]

Really, if we have a defined place where we construct the HCSM, we don't need to
do the lazy construction at all anyway.

Alternatively, we could check that GetHostContentSettingsMap() is only called on
the UI thread? That's a valid precondition, because Profile is UI-thread only.

[Jun Mukai, 2014/10/14 23:53:13]

Indeed, I was confused previously but we can add DCHECK in
GetHostContentSettingsMap() (ProfileIOData has the pointer to the instance, but
it invokes GetHostContentSettingsMap in UI thread and then remembers the value).
 Fixed.

+  GetHostContentSettingsMap();
+
   base::Callback<void(bool)> data_reduction_proxy_unavailable;
   scoped_ptr<data_reduction_proxy::DataReductionProxyParams>
       data_reduction_proxy_params;