Initial error handling code

src/core/SkOrderedWriteBuffer.cpp

Index: src/core/SkOrderedWriteBuffer.cpp
diff --git a/src/core/SkOrderedWriteBuffer.cpp b/src/core/SkOrderedWriteBuffer.cpp
index 64f52193acaf7c55dab611a5b53f41f13685fd7e..fd39a8e52102ba984cef59d07cd4bf703f020883 100644
--- a/src/core/SkOrderedWriteBuffer.cpp
+++ b/src/core/SkOrderedWriteBuffer.cpp
@@ -270,7 +270,10 @@ void SkOrderedWriteBuffer::writeFlattenable(SkFlattenable* flattenable) {
         factory = flattenable->getFactory();
     }
     if (NULL == factory) {
-        if (fFactorySet != NULL || fNamedFactorySet != NULL) {
+        if (this->isValidating()) {
+            this->writeString("");
+            SkASSERT(NULL == flattenable); // We shouldn't get in here in this scenario

[sugoi1, 2013/10/07 15:54:08]

I made a small change here, since NULL flattenable is a valid state here.

[mtklein, 2013/10/07 19:29:56]

Huh.  Have you seen a NULL flattenable come through here?  It'd surprise me if
we were going through here with a NULL intentionally.

[sugoi1, 2013/10/08 20:23:10]

Yes, in SkXfermodeImageFilter, fMode can be NULL, and we unconditionally call
buffer.writeFlattenable(fMode) inside SkXfermodeImageFilter::flatten() (found by
the fuzzer).

+        } else if (fFactorySet != NULL || fNamedFactorySet != NULL) {
             this->write32(0);
         } else {
             this->writeFunctionPtr(NULL);
@@ -290,7 +293,9 @@ void SkOrderedWriteBuffer::writeFlattenable(SkFlattenable* flattenable) {
      *      name. SkGPipe uses this technique so it can write the name to its
      *      stream before writing the flattenable.
      */
-    if (fFactorySet) {
+    if (this->isValidating()) {
+        this->writeString(flattenable->getFlattenableName());
+    } else if (fFactorySet) {
         this->write32(fFactorySet->add(factory));
     } else if (fNamedFactorySet) {
         int32_t index = fNamedFactorySet->find(factory);