Reduced the complexity of layers composition.

This change also refactors the code base a bit by moving classes out of
OpenGLRenderer into separate headers/implementations. This makes the code
more manageable.

This change also adds documentation for implementation methods. The
undocumented methods are simply Skia's Canvas methods.

Change-Id: I54c68b443580a0129251dddc1a7ac95813d5289e
diff --git a/libs/hwui/Rect.h b/libs/hwui/Rect.h
index b382dc3..ad57550 100644
--- a/libs/hwui/Rect.h
+++ b/libs/hwui/Rect.h
@@ -17,6 +17,8 @@
 #ifndef ANDROID_UI_RECT_H
 #define ANDROID_UI_RECT_H
 
+#include <utils/Log.h>
+
 namespace android {
 namespace uirenderer {