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/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index fc8d3dd..e56cba1 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -6,7 +6,8 @@
  */
 
 #include "SkDisplacementMapEffect.h"
-#include "SkFlattenableBuffers.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
 #include "SkUnPreMultiply.h"
 #include "SkColorPriv.h"
 #if SK_SUPPORT_GPU
@@ -172,7 +173,7 @@
 SkDisplacementMapEffect::~SkDisplacementMapEffect() {
 }
 
-SkDisplacementMapEffect::SkDisplacementMapEffect(SkFlattenableReadBuffer& buffer)
+SkDisplacementMapEffect::SkDisplacementMapEffect(SkReadBuffer& buffer)
   : INHERITED(2, buffer)
 {
     fXChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
@@ -183,7 +184,7 @@
                     SkScalarIsFinite(fScale));
 }
 
-void SkDisplacementMapEffect::flatten(SkFlattenableWriteBuffer& buffer) const {
+void SkDisplacementMapEffect::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeInt((int) fXChannelSelector);
     buffer.writeInt((int) fYChannelSelector);