Refactor read and write buffers.

Eliminates SkFlattenable{Read,Write}Buffer, promoting SkOrdered{Read,Write}Buffer
a step each in the hierarchy.

What used to be this:

SkFlattenableWriteBuffer -> SkOrderedWriteBuffer
SkFlattenableReadBuffer  -> SkOrderedReadBuffer
SkFlattenableReadBuffer  -> SkValidatingReadBuffer

is now

SkWriteBuffer
SkReadBuffer -> SkValidatingReadBuffer

Benefits:
  - code is simpler, names are less wordy
  - the generic SkFlattenableFooBuffer code in SkPaint was incorrect; removed
  - write buffers are completely devirtualized, important for record speed

This refactoring was mostly mechanical.  You aren't going to find anything
interesting in files with less than 10 lines changed.

BUG=skia:
R=reed@google.com, scroggo@google.com, djsollen@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/134163010

git-svn-id: http://skia.googlecode.com/svn/trunk@13245 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/imagefiltersgraph.cpp b/gm/imagefiltersgraph.cpp
index f5eaa28..40b673c 100644
--- a/gm/imagefiltersgraph.cpp
+++ b/gm/imagefiltersgraph.cpp
@@ -13,7 +13,8 @@
 #include "SkColorFilter.h"
 #include "SkColorFilterImageFilter.h"
 #include "SkColorMatrixFilter.h"
-#include "SkFlattenableBuffers.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
 #include "SkMergeImageFilter.h"
 #include "SkMorphologyImageFilter.h"
 #include "SkOnce.h"
@@ -57,13 +58,13 @@
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SimpleOffsetFilter);
 
 protected:
-    explicit SimpleOffsetFilter(SkFlattenableReadBuffer& buffer)
+    explicit SimpleOffsetFilter(SkReadBuffer& buffer)
     : SkImageFilter(1, buffer) {
         fDX = buffer.readScalar();
         fDY = buffer.readScalar();
     }
 
-    virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE {
+    virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE {
         this->SkImageFilter::flatten(buffer);
         buffer.writeScalar(fDX);
         buffer.writeScalar(fDY);