Disable ProfileKeyedServices on import process by default.

chrome/browser/webdata/web_data_service.cc

Index: chrome/browser/webdata/web_data_service.cc
diff --git a/chrome/browser/webdata/web_data_service.cc b/chrome/browser/webdata/web_data_service.cc
index f36d92a52e76f007b1fbb7b57c1186bcf0f1580f..551251a7e13acb5da969d0211759d2757f602362 100644
--- a/chrome/browser/webdata/web_data_service.cc
+++ b/chrome/browser/webdata/web_data_service.cc
@@ -87,10 +87,14 @@ WebDataService::WebDataService()
       failed_init_(false),
       should_commit_(false),
       main_loop_(MessageLoop::current()) {
+  // WebDataService takes ownership of a non-sharable resource (Web Data DB
+  // file) and so should never be launched on the import process, as it can
+  // grab the resource before the main browser process does.
+  CHECK(!ProfileManager::IsImportProcess(*CommandLine::ForCurrentProcess()));

[gab, 2013/03/07 15:46:57]

FWIW, we (me and macourteau) were hitting the DCHECK below when using
import_search_engine in master_preferences (http://crbug.com/180306); we are
investigating the root cause, but making this a CHECK will cause the import
process to crash for everyone using that preference...

+
   // WebDataService requires DB thread if instantiated.
   // Set WebDataServiceFactory::GetInstance()->SetTestingFactory(&profile, NULL)
   // if you do not want to instantiate WebDataService in your test.
-  DCHECK(!ProfileManager::IsImportProcess(*CommandLine::ForCurrentProcess()));
   DCHECK(BrowserThread::IsWellKnownThread(BrowserThread::DB));
 }