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/src/effects/SkTestImageFilters.cpp b/src/effects/SkTestImageFilters.cpp
index cc6d1ad..96226f5 100755
--- a/src/effects/SkTestImageFilters.cpp
+++ b/src/effects/SkTestImageFilters.cpp
@@ -2,7 +2,8 @@
 #include "SkTestImageFilters.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
-#include "SkFlattenableBuffers.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
 
 // Simple helper canvas that "takes ownership" of the provided device, so that
 // when this canvas goes out of scope, so will its device. Could be replaced
@@ -70,13 +71,13 @@
     return true;
 }
 
-void SkDownSampleImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
+void SkDownSampleImageFilter::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
     buffer.writeScalar(fScale);
 }
 
-SkDownSampleImageFilter::SkDownSampleImageFilter(SkFlattenableReadBuffer& buffer)
+SkDownSampleImageFilter::SkDownSampleImageFilter(SkReadBuffer& buffer)
   : INHERITED(1, buffer) {
     fScale = buffer.readScalar();
     buffer.validate(SkScalarIsFinite(fScale));