mash: Have chrome set itself as the wallpaper picker.

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
index d633dd17d1e2c004c48050efa2868fffbfe6785f..b1a2d71c2a96184e122d7ebb82c3ca8adfae68b6 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
@@ -369,11 +369,6 @@ void WallpaperManager::Shutdown() {
   wallpaper_manager = nullptr;
 }
 
-void WallpaperManager::BindRequest(
-    ash::mojom::WallpaperManagerRequest request) {
-  bindings_.AddBinding(this, std::move(request));
-}
-
 WallpaperManager::WallpaperResolution
 WallpaperManager::GetAppropriateResolution() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -807,7 +802,7 @@ void WallpaperManager::UpdateWallpaper(bool clear_cache) {
 // WallpaperManager, private: --------------------------------------------------
 
 WallpaperManager::WallpaperManager()
-    : pending_inactive_(NULL), weak_factory_(this) {
+    : binding_(this), pending_inactive_(nullptr), weak_factory_(this) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   wallpaper::WallpaperManagerBase::SetPathIds(
       chrome::DIR_USER_DATA, chrome::DIR_CHROMEOS_WALLPAPERS,
@@ -828,6 +823,18 @@ WallpaperManager::WallpaperManager()
               sequence_token_, base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
 
   user_manager::UserManager::Get()->AddSessionStateObserver(this);
+
+  content::ServiceManagerConnection* connection =
+      content::ServiceManagerConnection::GetForProcess();
+  if (connection && connection->GetConnector()) {

[James Cook, 2016/12/07 23:03:47]

Are you sure these can be null? Is that in tests?

I've written code that doesn't test for null for these... now I'm worried about
my code.

[msw, 2016/12/07 23:12:55]

Yes, the earlier patch sets failed because the connection is null; I verified
that locally. I think the potential for null is dependent upon the testing
conditions. This object is constructed in unit tests that don't initialize the
connection, but other connection users may not be invoked in such tests...

+    // Connect to the wallpaper controller interface in the ash service.
+    ash::mojom::WallpaperControllerPtr wallpaper_controller_ptr;
+    connection->GetConnector()->ConnectToInterface(
+        ash_util::GetAshServiceName(), &wallpaper_controller_ptr);
+    // Register this object as the wallpaper picker.
+    wallpaper_controller_ptr->SetWallpaperPicker(
+        binding_.CreateInterfacePtrAndBind());
+  }
 }
 
 WallpaperManager::PendingWallpaper* WallpaperManager::GetPendingWallpaper(