MD Settings: Display: Add unified desktop control and modify api

chrome/browser/extensions/display_info_provider_chromeos.cc

Index: chrome/browser/extensions/display_info_provider_chromeos.cc
diff --git a/chrome/browser/extensions/display_info_provider_chromeos.cc b/chrome/browser/extensions/display_info_provider_chromeos.cc
index a5a37a74f93a246a19855aaf45ad1c1d57b846b3..5fb965bb5673a4f54e4461a7a3c0f5ebb8a0d856 100644
--- a/chrome/browser/extensions/display_info_provider_chromeos.cc
+++ b/chrome/browser/extensions/display_info_provider_chromeos.cc
@@ -619,8 +619,11 @@ void DisplayInfoProviderChromeOS::EnableUnifiedDesktop(bool enable) {
     NOTIMPLEMENTED();
     return;
   }
-  ash::Shell::GetInstance()->display_manager()->SetUnifiedDesktopEnabled(
-      enable);
+  ash::Shell::GetInstance()
+      ->display_manager()
+      ->SetDefaultMultiDisplayModeForCurrentDisplays(
+          enable ? display::DisplayManager::UNIFIED
+                 : display::DisplayManager::EXTENDED);
 }
 
 DisplayInfoProvider::DisplayUnitInfoList
@@ -635,18 +638,19 @@ DisplayInfoProviderChromeOS::GetAllDisplaysInfo() {
   if (!display_manager->IsInUnifiedMode())
     return DisplayInfoProvider::GetAllDisplaysInfo();
 
-  std::vector<display::Display> displays =
-      display_manager->software_mirroring_display_list();
-  CHECK_GT(displays.size(), 0u);
+  // Chrome OS specific: get displays for unified mode.
+  std::vector<display::Display> displays;
+  for (size_t i = 0; i < display_manager->GetNumDisplays(); ++i)
+    displays.push_back(display_manager->GetDisplayAt(i));
 
-  // Use first display as primary.
-  int64_t primary_id = displays[0].id();
+  int64_t primary_id = display::Screen::GetScreen()->GetPrimaryDisplay().id();
   DisplayUnitInfoList all_displays;
   for (const display::Display& display : displays) {
-    system_display::DisplayUnitInfo unit =
+    system_display::DisplayUnitInfo unit_info =
         CreateDisplayUnitInfo(display, primary_id);
-    UpdateDisplayUnitInfoForPlatform(display, &unit);
-    all_displays.push_back(std::move(unit));
+    UpdateDisplayUnitInfoForPlatform(display, &unit_info);
+    unit_info.is_unified = true;

[xiyuan, 2017/04/05 21:41:45]

Can you document why we are doing this? I was puzzled initially then figured
that out after I saw line 638-639 that this code only runs for unified mode.

[stevenjb, 2017/04/06 01:56:08]

That was the intent of the comment at line 641 :) I'm not sure how much a
comment here will help.

+    all_displays.push_back(std::move(unit_info));
   }
   return all_displays;
 }