Return identity matrix when rendering in an FBO.

Change-Id: I57438e745b30c8cfe16c269f3cafcd719049d705

libs/hwui/OpenGLRenderer.cpp

@@ -585,7 +585,10 @@ void OpenGLRenderer::setMatrix(SkMatrix* matrix) {
 }
 
 const float* OpenGLRenderer::getMatrix() const {
-    return &mSnapshot->transform->data[0];
+    if (mSnapshot->fbo != 0) {
+        return &mSnapshot->transform->data[0];
+    }
+    return &mIdentity.data[0];
 }
 
 void OpenGLRenderer::getMatrix(SkMatrix* matrix) {

libs/hwui/OpenGLRenderer.h

@@ -432,6 +432,9 @@ private:
     // Misc
     GLint mMaxTextureSize;
 
+    // Indentity matrix
+    const mat4 mIdentity;
+
     friend class DisplayListRenderer;
 
 }; // class OpenGLRenderer