Extract colors from wallpaper and dynamically update login screen overlay

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

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
index cefafb3734460443239feb5ed5594c6acde51c75..29d40d491ef3ad4b83af1d0b2db29f1410606e4a 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "ash/public/interfaces/wallpaper.mojom.h"
+#include "ash/shelf/shelf_constants.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/weak_ptr.h"
@@ -19,12 +20,15 @@
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_image/user_image.h"
 #include "components/user_manager/user_manager.h"
+#include "components/wallpaper/wallpaper_color_calculator.h"
+#include "components/wallpaper/wallpaper_color_calculator_observer.h"
 #include "components/wallpaper/wallpaper_layout.h"
 #include "components/wallpaper/wallpaper_manager_base.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "ui/aura/window_observer.h"
+#include "ui/gfx/color_utils.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/wm/public/activation_change_observer.h"
 #include "ui/wm/public/activation_client.h"
@@ -113,6 +117,17 @@ class WallpaperManager
   // aura::WindowObserver:
   void OnWindowDestroying(aura::Window* window) override;
 
+  // Setting a non-NULL observer indicates that color calculation is needed

[jdufault, 2017/06/10 03:05:59]

nit: non-null

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

+  // when a wallpaper is set.

[jdufault, 2017/06/10 03:05:59]

Generally, try to avoid encoding state information in a null/non-null value. Use
base::Optional for that instead, as it conveys more semantic meaning.

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

+  void SetLoginOverlayCalculatorObserver(

[jdufault, 2017/06/10 03:05:59]

These functions should go above the overrides (overrides go last).

[jdufault, 2017/06/10 03:05:59]

This should follow the standard AddObserver/RemoveObserver pattern. See
base::ObserverList. Register SigninScreenHandler as an observer on construction,
and deregister in SigninScreenHandler dtor.

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

+      wallpaper::WallpaperColorCalculatorObserver*);

[jdufault, 2017/06/10 03:05:59]

Set a variable name here.

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

+
+  // Must be called after color calculation succeeds. Get the actual colors
+  // which will be used in login screen based on the prominent color.
+  void getLoginOverlayColors(std::string* dm_color,

[jdufault, 2017/06/10 03:05:59]

nit: Out parameters should have out_ prefix.

[jdufault, 2017/06/10 03:05:59]

nit: get -> Get

[Wenzhao (Colin) Zang, 2017/06/12 21:10:57]

Done.

[Wenzhao (Colin) Zang, 2017/06/12 21:10:57]

Done.

+                             std::string* scroll_color,
+                             std::string* background_color);
+
  private:
   friend class TestApi;
   friend class WallpaperManagerBrowserTest;
@@ -159,6 +174,11 @@ class WallpaperManager
       const AccountId& account_id,
       std::unique_ptr<user_manager::UserImage> user_image);
 
+  // If the calculator observer is not NULL, calculate a prominent color based

[jdufault, 2017/06/10 03:05:59]

nit: NULL -> null

[Wenzhao (Colin) Zang, 2017/06/12 21:10:58]

Done.

+  // on the wallpaper image. An existing calculation in progress (if any) will
+  // be destroyed first.
+  void CalculateProminentColor(const gfx::ImageSkia& image);
+
   // wallpaper::WallpaperManagerBase:
   void InitializeRegisteredDeviceWallpaper() override;
   bool GetUserWallpaperInfo(const AccountId& account_id,
@@ -240,6 +260,11 @@ class WallpaperManager
 
   base::WeakPtrFactory<WallpaperManager> weak_factory_;
 
+  std::unique_ptr<wallpaper::WallpaperColorCalculator> color_calculator_;
+
+  wallpaper::WallpaperColorCalculatorObserver*
+      login_overlay_calculator_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(WallpaperManager);
 };