Support rendering white pixels.

This CL allows dynamic color boot animations to render graphics in shades of white.

Bug: 190093578
Test: adb shell stop; adb shell start. Complete reboot to see the full
sequence (including the loader part)

Change-Id: I672a49aff90fa04daa4bdd6fd3c0b5497cc1a115
diff --git a/cmds/bootanimation/BootAnimation.h b/cmds/bootanimation/BootAnimation.h
index 0e29621..7a597da 100644
--- a/cmds/bootanimation/BootAnimation.h
+++ b/cmds/bootanimation/BootAnimation.h
@@ -111,6 +111,8 @@
         Font progressFont;
          // Controls if dynamic coloring is enabled for the whole animation.
         bool dynamicColoringEnabled = false;
+        int colorTransitionStart = 0; // Start frame of dynamic color transition.
+        int colorTransitionEnd = 0; // End frame of dynamic color transition.
         float startColors[4][3]; // Start colors of dynamic color transition.
         float endColors[4][3];   // End colors of dynamic color transition.
     };