Remove unused functions and variables from DisplayListCanvas

This also moves some functions that are only called when creating/completing
a displayList into the appropriate constructors and endRecording calls.

Change-Id: I9f6add156d7f476a52766934af713b0f852c8dea
diff --git a/libs/hwui/tests/main.cpp b/libs/hwui/tests/main.cpp
index 80d7029..64d9037 100644
--- a/libs/hwui/tests/main.cpp
+++ b/libs/hwui/tests/main.cpp
@@ -42,15 +42,12 @@
 };
 
 static DisplayListCanvas* startRecording(RenderNode* node) {
-    DisplayListCanvas* renderer = new DisplayListCanvas();
-    renderer->setViewport(node->stagingProperties().getWidth(),
-            node->stagingProperties().getHeight());
-    renderer->prepare();
+    DisplayListCanvas* renderer = new DisplayListCanvas(
+            node->stagingProperties().getWidth(), node->stagingProperties().getHeight());
     return renderer;
 }
 
 static void endRecording(DisplayListCanvas* renderer, RenderNode* node) {
-    renderer->finish();
     node->setStagingDisplayList(renderer->finishRecording());
     delete renderer;
 }