Allow SessionBackend::Init() to occur just-in-time in production builds.

chrome/browser/sessions/base_session_service.cc

Index: chrome/browser/sessions/base_session_service.cc
diff --git a/chrome/browser/sessions/base_session_service.cc b/chrome/browser/sessions/base_session_service.cc
index 6991e24c4294cd7693bd9d50b3eaa5941650cd1a..a529d31c4026a4d8c830d3e699cbcd2ae52f8064 100644
--- a/chrome/browser/sessions/base_session_service.cc
+++ b/chrome/browser/sessions/base_session_service.cc
@@ -91,8 +91,15 @@ BaseSessionService::BaseSessionService(SessionType type,
       profile_ ? profile_->GetPath() : path_);
   DCHECK(backend_.get());
 
-  RunTaskOnBackendThread(FROM_HERE,
-                         base::Bind(&SessionBackend::Init, backend_));
+  if (!RunningInProduction()) {
+    // We seem to be running as part of a test, in which case we need
+    // to explicitly initialize the backend.  In production, the
+    // backend will automatically initialize itself just in time.
+    //
+    // Note that it's important not to initialize too early in
+    // production; this can cause e.g. http://crbug.com/110785.
+    backend_->Init();
+  }
 }
 
 BaseSessionService::~BaseSessionService() {
@@ -322,10 +329,14 @@ BaseSessionService::Handle BaseSessionService::ScheduleGetLastSessionCommands(
   return request->handle();
 }
 
+bool BaseSessionService::RunningInProduction() const {
+  return profile_ && BrowserThread::IsMessageLoopValid(BrowserThread::FILE);
+}
+
 bool BaseSessionService::RunTaskOnBackendThread(
     const tracked_objects::Location& from_here,
     const base::Closure& task) {
-  if (profile_ && BrowserThread::IsMessageLoopValid(BrowserThread::FILE)) {
+  if (RunningInProduction()) {
     return BrowserThread::PostTask(BrowserThread::FILE, from_here, task);
   } else {
     // Fall back to executing on the main thread if the file thread