[Night Light] CL2: Ash and system tray work

ash/system/tiles/tiles_default_view.cc

Index: ash/system/tiles/tiles_default_view.cc
diff --git a/ash/system/tiles/tiles_default_view.cc b/ash/system/tiles/tiles_default_view.cc
index d5c51a7eef4766fc5a4b277e7cd11d70a17242b1..40a691f79298a58104db9829e06454504d23912c 100644
--- a/ash/system/tiles/tiles_default_view.cc
+++ b/ash/system/tiles/tiles_default_view.cc
@@ -11,6 +11,7 @@
 #include "ash/shell_port.h"
 #include "ash/shutdown_controller.h"
 #include "ash/strings/grit/ash_strings.h"
+#include "ash/system/night_light/night_light_controller.h"
 #include "ash/system/tray/system_menu_button.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_controller.h"
@@ -41,6 +42,7 @@ TilesDefaultView::TilesDefaultView(SystemTrayItem* owner)
     : owner_(owner),
       settings_button_(nullptr),
       help_button_(nullptr),
+      night_light_button_(nullptr),
       lock_button_(nullptr),
       power_button_(nullptr) {
   DCHECK(owner_);
@@ -85,6 +87,16 @@ void TilesDefaultView::Init() {
   AddChildView(help_button_);
   AddChildView(TrayPopupUtils::CreateVerticalSeparator());
 
+  night_light_button_ = new SystemMenuButton(
+      this, TrayPopupInkDropStyle::HOST_CENTERED,
+      ash::Shell::Get()->night_light_controller()->enabled()

[James Cook, 2017/05/05 17:12:32]

nit: no ash::

[afakhry, 2017/05/05 20:04:12]

Done.

+          ? kSystemMenuNightLightOnIcon
+          : kSystemMenuNightLightOffIcon,
+      IDS_ASH_STATUS_TRAY_NIGHT_LIGHT);
+  night_light_button_->SetEnabled(!disable_buttons);

[James Cook, 2017/05/05 17:12:32]

Is this button going to be a toggle, or will it open WebUI settings?

If the former, this should not use |disable_buttons|.

[afakhry, 2017/05/05 20:04:12]

It's a toggle button, but this |disable_buttons| is still needed because before
login, it makes all these buttons disabled and grayed out.

[James Cook, 2017/05/05 20:47:43]

|disable_buttons| currently means "I can show webui settings". It only sort-of
means you're at the login screen - there are lots of other cases where it is
true.

I suggest renaming |disable_buttons| to |can_show_webui| and inversing the
logic, then adding the conditional you really mean here (maybe
SessionController::IsActiveUserSession, IsScreenLocked, or some combination
thereof).

If you really want CanOpenWebUISettings you need a comment explaining why you're
using that even though the button does not open webui, and/or rename the
CanOpenWebUISettings method.

[afakhry, 2017/05/06 00:49:34]

According to this comment:
https://cs.chromium.org/chromium/src/ash/system/tiles/tiles_default_view.cc?t...
One can't open WebUI Settings in login screen, lock screen, or secondary account
flow. If that's true, it's also what we want for the Night Light toggle button;
we want it disabled in all the above situations. 

I modified |disabled_buttons| to |can_show_web_ui| as requested.

Do I still need to check IsActiveUserSession() or IsScreenLocked() etc? It seems
from the above comment that |can_show_web_ui| is enough.

+  AddChildView(night_light_button_);
+  AddChildView(TrayPopupUtils::CreateVerticalSeparator());

[James Cook, 2017/05/05 17:12:32]

Please add a test that the night light icon is created in the correct state. For
example, see TrayTilesTest.

[afakhry, 2017/05/05 20:04:12]

Done. I updated TrayTilesTest.

+
   lock_button_ =
       new SystemMenuButton(this, TrayPopupInkDropStyle::HOST_CENTERED,
                            kSystemMenuLockIcon, IDS_ASH_STATUS_TRAY_LOCK);
@@ -114,6 +126,9 @@ void TilesDefaultView::ButtonPressed(views::Button* sender,
   } else if (sender == help_button_) {
     ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_HELP);
     Shell::Get()->system_tray_controller()->ShowHelp();
+  } else if (sender == night_light_button_) {
+    ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_NIGHT_LIGHT);
+    Shell::Get()->night_light_controller()->Toggle();
   } else if (sender == lock_button_) {
     ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_LOCK_SCREEN);
     chromeos::DBusThreadManager::Get()