Simplify flattening to just write enough to call the factory/public-constructor for the class. We want to *not* rely on private constructors, and not rely on calling through the inheritance hierarchy for either flattening or unflattening(CreateProc).

Refactoring pattern:

1. guard the existing constructor(readbuffer) with the legacy build-flag
2. If you are a instancable subclass, implement CreateProc(readbuffer) to create a new instances from the buffer params (or return NULL).

If you're a shader subclass
1. You must read/write the local matrix if your class accepts that in its factory/constructor, else ignore it.

R=robertphillips@google.com, mtklein@google.com, senorblanco@google.com, senorblanco@chromium.org, sugoi@chromium.org

Author: reed@google.com

Review URL: https://codereview.chromium.org/395603002
diff --git a/src/effects/SkLayerDrawLooper.cpp b/src/effects/SkLayerDrawLooper.cpp
index aed2c9b..19525ec 100644
--- a/src/effects/SkLayerDrawLooper.cpp
+++ b/src/effects/SkLayerDrawLooper.cpp
@@ -200,20 +200,6 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkLayerDrawLooper::flatten(SkWriteBuffer& buffer) const {
-    this->INHERITED::flatten(buffer);
-
-#ifdef SK_DEBUG
-    {
-        Rec* rec = fRecs;
-        int count = 0;
-        while (rec) {
-            rec = rec->fNext;
-            count += 1;
-        }
-        SkASSERT(count == fCount);
-    }
-#endif
-
     buffer.writeInt(fCount);
 
     Rec* rec = fRecs;
@@ -245,22 +231,7 @@
         info.fPostTranslate = buffer.readBool();
         buffer.readPaint(builder.addLayerOnTop(info));
     }
-    SkLayerDrawLooper* looper = builder.detachLooper();
-    SkASSERT(count == looper->fCount);
-
-#ifdef SK_DEBUG
-    {
-        Rec* rec = looper->fRecs;
-        int n = 0;
-        while (rec) {
-            rec = rec->fNext;
-            n += 1;
-        }
-        SkASSERT(count == n);
-    }
-#endif
-
-    return looper;
+    return builder.detachLooper();
 }
 
 #ifndef SK_IGNORE_TO_STRING