Set write buffer flags only in SkWriteBuffer and SkFlatController constructors.

src/core/SkWriteBuffer.cpp

Index: src/core/SkWriteBuffer.cpp
diff --git a/src/core/SkWriteBuffer.cpp b/src/core/SkWriteBuffer.cpp
index cbbb4c94fc1926bca82ac18f2fd661a1802678d3..a295a8c88c2b05be4e8c28eb4a445e3788dc2c9b 100644
--- a/src/core/SkWriteBuffer.cpp
+++ b/src/core/SkWriteBuffer.cpp
@@ -14,8 +14,8 @@
 #include "SkStream.h"
 #include "SkTypeface.h"
 
-SkWriteBuffer::SkWriteBuffer()
-    : fFlags(0)
+SkWriteBuffer::SkWriteBuffer(uint32_t flags)
+    : fFlags(flags)
     , fFactorySet(NULL)
     , fNamedFactorySet(NULL)
     , fBitmapHeap(NULL)
@@ -23,8 +23,8 @@ SkWriteBuffer::SkWriteBuffer()
     , fBitmapEncoder(NULL) {
 }
 
-SkWriteBuffer::SkWriteBuffer(void* storage, size_t storageSize)
-    : fFlags(0)
+SkWriteBuffer::SkWriteBuffer(void* storage, size_t storageSize, uint32_t flags)
+    : fFlags(flags)
     , fFactorySet(NULL)
     , fNamedFactorySet(NULL)
     , fWriter(storage, storageSize)