Encapsulate textures into their own Texture class

the main reason for doing this is so that we can have
access to informations about a texture (like its dimension)
close to where we generate and use shaders in ES 2.0.
Previously, there wasn't any way to get to a texture's size
from a RenderEngine implementation.

Bug: 8679321

Change-Id: I388b338a70d07e3e8177dde248710ea1e4c82dff
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index faf3666..ef4a7e9 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -45,6 +45,7 @@
 #include "DisplayHardware/HWComposer.h"
 #include "DisplayHardware/FloatRect.h"
 #include "RenderEngine/Mesh.h"
+#include "RenderEngine/Texture.h"
 
 namespace android {
 
@@ -359,6 +360,8 @@
     bool mNeedsFiltering;
     // The mesh used to draw the layer in GLES composition mode
     mutable Mesh mMesh;
+    // The mesh used to draw the layer in GLES composition mode
+    mutable Texture mTexture;
 
     // page-flip thread (currently main thread)
     bool mSecure; // no screenshots