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/SkLayerDrawLooper.cpp b/src/effects/SkLayerDrawLooper.cpp
index 65f058b..6c7c3ce 100644
--- a/src/effects/SkLayerDrawLooper.cpp
+++ b/src/effects/SkLayerDrawLooper.cpp
@@ -7,7 +7,8 @@
  */
 #include "SkCanvas.h"
 #include "SkColor.h"
-#include "SkFlattenableBuffers.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
 #include "SkLayerDrawLooper.h"
 #include "SkString.h"
 #include "SkStringUtils.h"
@@ -191,7 +192,7 @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
-void SkLayerDrawLooper::flatten(SkFlattenableWriteBuffer& buffer) const {
+void SkLayerDrawLooper::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
 #ifdef SK_DEBUG
@@ -220,7 +221,7 @@
     }
 }
 
-SkLayerDrawLooper::SkLayerDrawLooper(SkFlattenableReadBuffer& buffer)
+SkLayerDrawLooper::SkLayerDrawLooper(SkReadBuffer& buffer)
         : INHERITED(buffer),
           fRecs(NULL),
           fTopRec(NULL),