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

ash/mus/bridge/wm_shell_mus.cc

Index: ash/mus/bridge/wm_shell_mus.cc
diff --git a/ash/mus/bridge/wm_shell_mus.cc b/ash/mus/bridge/wm_shell_mus.cc
index 78959a48aad559e9114e08841a787df655b60d2d..af64351cb807cf0694866cc5658ee6527e481108 100644
--- a/ash/mus/bridge/wm_shell_mus.cc
+++ b/ash/mus/bridge/wm_shell_mus.cc
@@ -140,8 +140,7 @@ WmShellMus::WmShellMus(
   // TODO(jamescook): Port ash::sysui::KeyboardUIMus and use it here.
   SetKeyboardUI(KeyboardUI::Create());
 
-  // TODO(msw): Port WallpaperDelegateMus and support this (crbug.com/629605):
-  // wallpaper_delegate()->InitializeWallpaper();
+  wallpaper_delegate()->InitializeWallpaper();
 }
 
 WmShellMus::~WmShellMus() {
@@ -231,6 +230,26 @@ const display::ManagedDisplayInfo& WmShellMus::GetDisplayInfo(
     int64_t display_id) const {
   // TODO(mash): implement http://crbug.com/622480.
   NOTIMPLEMENTED();
+
+  // Return a stub ManagedDisplayInfo object created from a Display object.

[msw, 2016/09/09 19:10:04]

Let me know if there's a better way to do this at the moment...

[kylechar, 2016/09/09 20:12:35]

Hmm, this is probably the wrong thing to do here (although let's see if rjkroege
agrees). ManagedDisplayInfo is very closely coupled to the internals of
ash::DisplayManager and the display state. In cash, other parts of ash just use
whatever is inside ash::DisplayManager.

For mustash, display::PlatformDisplay (which is conceptually the same as
ash::DisplayManager and the two will be merged soon) will be in the mus process.
So ash can't just access the internals without a Mojo interface. We also want a
better API that exposes the absolutely minimum about display state. I've started
a really basic mojom::DisplayController and will be adding more to it.

So I guess I'm wondering what information does ash need from ManagedDisplayInfo
that isn't in the display::Display already? Instead of using ManagedDisplayInfo,
I can add to mojom::DisplayController or possibly some other Mojo interface as
needed.

[msw, 2016/09/09 21:13:08]

I uploaded an alternative workaround patch to appease the callers needed here:
- WallpaperController needs ManagedDisplayInfo::bounds_in_native().
- WallpaperView needs ManagedDisplayInfo::GetEffectiveUIScale().

The other active mus WmShell::GetDisplayInfo caller is:
- TrayAudio::ChangeInternalSpeakerChannelMode needs GetActiveRotation().

I don't know much offhand about the DisplayManager::GetDisplayInfo callers. It'd
be great if we could start using Display objects obtained from the
display::Screen instance, instead of ManagedDisplayInfo, but I'm not entirely
sure when that's possible (seems like Display::size() !=
ManagedDisplayInfo::bounds_in_native().size(), Display::device_scale_factor() !=
ManagedDisplayInfo::GetEffectiveUIScale(), perhaps Display::rotation() !=
ManagedDisplayInfo::GetRotation()/GetActiveRotation(), and I don't know if
Display does the right thing with callers that use InternalDisplayId, etc.).

+  auto info = display_info_map_.find(display_id);
+  if (info != display_info_map_.end())
+    return info->second;
+  for (const display::Display& display :
+       display::Screen::GetScreen()->GetAllDisplays()) {
+    if (display.id() == display_id) {
+      display::ManagedDisplayInfo info(display.id(), "MusDisplay", false);
+      info.SetBounds(display.bounds());
+      info.set_device_scale_factor(display.device_scale_factor());
+      info.SetRotation(display.rotation(),
+                       display::Display::ROTATION_SOURCE_UNKNOWN);
+      info.set_touch_support(display.touch_support());
+      info.set_maximum_cursor_size(display.maximum_cursor_size());
+      display_info_map_[display_id] = info;
+      return display_info_map_[display_id];
+    }
+  }
+
   static display::ManagedDisplayInfo fake_info;
   return fake_info;
 }