Update HWUI to store its own SkBitmap objects

This enables us to...

1) simplify the lifecycle/ownership between Java and HWUI
2) remove DisplayListRenderer::drawBitmapData and associated logic
3) track pixel lifecycle using standard SkPixelRef refcounting
4) Remove uncessary calls to ref/unref the bitmap's pixels and colorTable

Change-Id: I3c95078da20995444f6388a029414280fd654318
diff --git a/libs/hwui/TextureCache.cpp b/libs/hwui/TextureCache.cpp
index 7dc2480..b4d3708 100644
--- a/libs/hwui/TextureCache.cpp
+++ b/libs/hwui/TextureCache.cpp
@@ -233,11 +233,9 @@
     return texture;
 }
 
-void TextureCache::releaseTexture(const SkBitmap* bitmap) {
-    if (!bitmap || !bitmap->pixelRef()) return;
-
+void TextureCache::releaseTexture(uint32_t pixelRefStableID) {
     Mutex::Autolock _l(mLock);
-    mGarbage.push(bitmap->pixelRef()->getStableID());
+    mGarbage.push(pixelRefStableID);
 }
 
 void TextureCache::clearGarbage() {