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/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index d389d5e..722ff27 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -11,8 +11,8 @@
 #include "SkTypes.h"
 #include "SkSize.h"
 
-class SkFlattenableWriteBuffer;
-class SkFlattenableReadBuffer;
+class SkWriteBuffer;
+class SkReadBuffer;
 
 /**
  *  Describes how to interpret the alpha compoent of a pixel.
@@ -178,8 +178,8 @@
         return 0 != memcmp(this, &other, sizeof(other));
     }
 
-    void unflatten(SkFlattenableReadBuffer&);
-    void flatten(SkFlattenableWriteBuffer&) const;
+    void unflatten(SkReadBuffer&);
+    void flatten(SkWriteBuffer&) const;
 
     size_t getSafeSize(size_t rowBytes) const {
         if (0 == fHeight) {