Simplify flattening to just write enough to call the factory

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 3eb688e2c74d9848cfdd5a0028ecf159db7edfa7..b52976c8e347aa3f13acea981bc30f02bfc0a8f3 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -39,13 +39,13 @@ void SkImageFilter::Common::detachInputs(SkImageFilter** inputs) {
     sk_bzero(fInputs.get(), size);
 }
 
-bool SkImageFilter::Common::unflatten(SkReadBuffer& buffer, int expectedCount) {
+bool SkImageFilter::Common::unflatten(SkReadBuffer& buffer, int expectedInputCount) {
     int count = buffer.readInt();
-    if (expectedCount < 0) {    // means the caller doesn't care how many
-        expectedCount = count;
+    if (expectedInputCount < 0) {
+        expectedInputCount = count;
     }
-    if (!buffer.validate(count == expectedCount)) {
-        return false;
+    if (!buffer.validate(count == expectedInputCount)) {
+        return NULL;
     }
 
     this->allocInputs(count);
@@ -102,7 +102,7 @@ SkImageFilter::SkImageFilter(int inputCount, SkReadBuffer& buffer) {
     }
 }
 
-void SkImageFilter::flatten(SkWriteBuffer& buffer) const {
+void SkImageFilter::flattenCommon(SkWriteBuffer& buffer) const {
     buffer.writeInt(fInputCount);
     for (int i = 0; i < fInputCount; i++) {
         SkImageFilter* input = getInput(i);