Extracting more than one wallpaper prominent color

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h"
 
 #include <utility>
 
 #include "ash/ash_constants.h"
 #include "ash/public/cpp/shelf_types.h"
@@ skipping 45 matching lines @@
 #include "components/user_manager/user_type.h"
 #include "components/wallpaper/wallpaper_files_id.h"
 #include "components/wallpaper/wallpaper_layout.h"
 #include "components/wallpaper/wallpaper_resizer.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/service_manager_connection.h"
 #include "crypto/sha2.h"
 #include "services/service_manager/public/cpp/connector.h"
+#include "ui/gfx/color_analysis.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 using wallpaper::WallpaperManagerBase;
 using wallpaper::WallpaperInfo;
 using wallpaper::MovableOnDestroyCallback;
 using wallpaper::MovableOnDestroyCallbackHolder;
 
 namespace chromeos {
 
@@ skipping 361 matching lines @@
   return false;
 }
 
 void WallpaperManager::CalculateProminentColor(const gfx::ImageSkia& image) {
   // Cancel in-flight color calculations, if any.
   if (color_calculator_) {
     color_calculator_->RemoveObserver(this);
     color_calculator_.reset();
   }
 
+  // TODO(warx): this color fetching should go through ash::WallpaperController.
+  std::vector<color_utils::ColorProfile> color_profiles;
+  color_profiles.emplace_back(color_utils::LumaRange::DARK,
+                              color_utils::SaturationRange::MUTED);
   color_calculator_ = base::MakeUnique<wallpaper::WallpaperColorCalculator>(
-      image, color_utils::LumaRange::DARK, color_utils::SaturationRange::MUTED,
-      task_runner_);
+      image, color_profiles, task_runner_);
   color_calculator_->AddObserver(this);
   if (!color_calculator_->StartCalculation()) {
     color_calculator_->RemoveObserver(this);
     color_calculator_.reset();
     if (!prominent_color_.has_value())
       return;
     prominent_color_.reset();
     for (auto& observer : observers_)
       observer.OnWallpaperColorsChanged();
   }
@@ skipping 477 matching lines @@
   }
 }
 
 void WallpaperManager::OnWindowDestroying(aura::Window* window) {
   window_observer_.Remove(window);
   chromeos::WallpaperWindowStateManager::RestoreWindows(
       user_manager::UserManager::Get()->GetActiveUser()->username_hash());
 }
 
 void WallpaperManager::OnColorCalculationComplete() {
-  SkColor color = color_calculator_->prominent_color();
+  SkColor color = color_calculator_->prominent_colors()[0];

[bruthig, 2017/06/21 15:54:17]

'0' seems like a magic number here.

[Qiang(Joe) Xu, 2017/06/21 22:35:27]

Done.

   color_calculator_->RemoveObserver(this);
   color_calculator_.reset();
   if (prominent_color_ == color)
     return;
   prominent_color_ = color;
 
   for (auto& observer : observers_)
     observer.OnWallpaperColorsChanged();
 }
 
@@ skipping 536 matching lines @@
 
   UMA_HISTOGRAM_ENUMERATION(
       "Ash.Wallpaper.Apps",
       wallpaper_manager_util::ShouldUseAndroidWallpapersApp(profile)
           ? WALLPAPERS_APP_ANDROID
           : WALLPAPERS_PICKER_APP_CHROMEOS,
       WALLPAPERS_APPS_NUM);
 }
 
 }  // namespace chromeos