mash: Port sysui's WallpaperDelegateMus to mojo:ash.

ash/common/wallpaper/wallpaper_controller.cc

Index: ash/common/wallpaper/wallpaper_controller.cc
diff --git a/ash/common/wallpaper/wallpaper_controller.cc b/ash/common/wallpaper/wallpaper_controller.cc
index c0c60279758f9e46f64a779c7b46f2ef4cf05674..76864c6e04b3de1c6a3b1327fbf7f783a713ca59 100644
--- a/ash/common/wallpaper/wallpaper_controller.cc
+++ b/ash/common/wallpaper/wallpaper_controller.cc
@@ -151,8 +151,12 @@ gfx::Size WallpaperController::GetMaxDisplaySizeInNative() {
     // Display::size.
     // TODO(msw): Avoid using Display::size here; see http://crbug.com/613657.
     gfx::Size size = display.size();
-    if (shell)
-      size = shell->GetDisplayInfo(display.id()).bounds_in_native().size();
+    if (shell) {
+      display::ManagedDisplayInfo info = shell->GetDisplayInfo(display.id());
+      // TODO(mash): Mash returns a fake ManagedDisplayInfo. crbug.com/622480

[sky, 2016/09/09 22:17:01]

Is wallpaper the only place that needs ManagedDisplayInfo? If so, how about
providing methods for the specific data you need on WmShell rather than the more
generic ManagedDisplayInfo.

[msw, 2016/09/09 23:09:51]

No, many places currently use ManagedDisplayInfo. It seems like the path forward
for these workarounds are probably to move ManagedDisplayInfo::bounds_in_native
to display::Display, and just use display::Display::rotation(). I'd like to
address those in followup patches, unrelated to WallpaperDelegateMus.

[sky, 2016/09/09 23:36:35]

Ok, sounds reasonable to me to address fetching the ManagedDisplayInfo
separately. It may make sense to send it in the WindowManager interface if that
is the only place that needs it.

+      if (info.id() == display.id())
+        size = info.bounds_in_native().size();
+    }
     if (display.rotation() == display::Display::ROTATE_90 ||
         display.rotation() == display::Display::ROTATE_270) {
       size = gfx::Size(size.height(), size.width());