Update Launcher to use theme colors.

Instead of using hard-coded variants of colors, use the theme color
that corresponds (colorAccent, colorPrimary, etc).

Updated:
- "Search for more apps" text
- App info drop target hover color
- PageIndicatorDots
- All apps & widget scroll bar & scroll popup colors
- All apps section text color
- widget picker background color

TODO:
- widget picker header color

BUG: 28625102
Change-Id: I74b543ff71b8caef8cd950c8183ac84c759cb4d5

src/com/android/launcher3/widget/WidgetsContainerView.java

@@ -82,9 +82,9 @@ public class WidgetsContainerView extends BaseContainerView
 
     public WidgetsContainerView(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
-        mLauncher = (Launcher) context;
+        mLauncher = Launcher.getLauncher(context);
         mDragController = mLauncher.getDragController();
-        mAdapter = new WidgetsListAdapter(this, this, mLauncher);
+        mAdapter = new WidgetsListAdapter(this, this, context);
         mIconCache = (LauncherAppState.getInstance()).getIconCache();
         if (LOGD) {
             Log.d(TAG, "WidgetsContainerView constructor");