switch to use mat4

Change-Id: I8283a989cfd2b74d53958150bc90298bc083fee7
diff --git a/services/surfaceflinger/RenderEngine/Description.cpp b/services/surfaceflinger/RenderEngine/Description.cpp
index 8e404b2..b0325c6 100644
--- a/services/surfaceflinger/RenderEngine/Description.cpp
+++ b/services/surfaceflinger/RenderEngine/Description.cpp
@@ -33,9 +33,7 @@
     mOpaque = true;
     mTextureEnabled = false;
 
-    const GLfloat m[16] = {1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1 };
     memset(mColor, 0, sizeof(mColor));
-    memcpy(mProjectionMatrix, m, sizeof(mProjectionMatrix));
 }
 
 Description::~Description() {
@@ -78,8 +76,8 @@
     mUniformsDirty = true;
 }
 
-void Description::setProjectionMatrix(GLfloat const* mtx) {
-    memcpy(mProjectionMatrix, mtx, sizeof(mProjectionMatrix));
+void Description::setProjectionMatrix(const mat4& mtx) {
+    mProjectionMatrix = mtx;
     mUniformsDirty = true;
 }