Added ColorExtractionService and ExtractedColors.

- Launcher has an instance of ExtractedColors, which is loaded from
  LauncherProvider in onCreate() and whenever the wallpaper changes.
  - When the wallpaper changes, the ColorExtractionService is started
    in the :wallpaper-chooser process.
  - ColorExtractionService builds an ExtractedColors instance and saves
    it as a String in LauncherProvider.
  - When the results are saved, Launcher gets a callback through
    LauncherProviderChangeListener and reloads the ExtractedColors.
- Whenever Launcher loads Extractecolors, it also re-colors items
  (currently a no-op).

Change-Id: I319e2cfe0a86abcbc6bb39ef6b9fbbcad54ad743
diff --git a/src/com/android/launcher3/LauncherModel.java b/src/com/android/launcher3/LauncherModel.java
index 3c7366c..f6a067c 100644
--- a/src/com/android/launcher3/LauncherModel.java
+++ b/src/com/android/launcher3/LauncherModel.java
@@ -54,6 +54,7 @@
 import com.android.launcher3.compat.UserHandleCompat;
 import com.android.launcher3.compat.UserManagerCompat;
 import com.android.launcher3.config.ProviderConfig;
+import com.android.launcher3.dynamicui.ExtractionUtils;
 import com.android.launcher3.folder.Folder;
 import com.android.launcher3.folder.FolderIcon;
 import com.android.launcher3.model.GridSizeMigrationTask;
@@ -1237,6 +1238,8 @@
                         PackageUpdatedTask.OP_USER_AVAILABILITY_CHANGE,
                         new String[0], user));
             }
+        } else if (Intent.ACTION_WALLPAPER_CHANGED.equals(action)) {
+            ExtractionUtils.startColorExtractionServiceIfNecessary(context);
         }
     }