clarify that accessPixels is for write-access, and peekPixels is RO

src/core/SkBitmapDevice.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapDevice.h"
 #include "SkConfig8888.h"
 #include "SkDeviceProperties.h"
@@ skipping 108 matching lines @@
 SkBaseDevice* SkBitmapDevice::onCreateDevice(const CreateInfo& cinfo, const SkPaint*) {
     SkDeviceProperties leaky(cinfo.fPixelGeometry);
     return SkBitmapDevice::Create(cinfo.fInfo, &leaky);
 }
 
 const SkBitmap& SkBitmapDevice::onAccessBitmap() {
     return fBitmap;
 }
 
 bool SkBitmapDevice::onAccessPixels(SkPixmap* pmap) {
-    return fBitmap.lockPixelsAreWritable() && this->onPeekPixels(pmap);
+    if (fBitmap.lockPixelsAreWritable() && this->onPeekPixels(pmap)) {
+        fBitmap.notifyPixelsChanged();
+        return true;
+    }
+    return false;
 }
 
 bool SkBitmapDevice::onPeekPixels(SkPixmap* pmap) {
     const SkImageInfo info = fBitmap.info();
     if (fBitmap.getPixels() && (kUnknown_SkColorType != info.colorType())) {
         SkColorTable* ctable = NULL;
         pmap->reset(fBitmap.info(), fBitmap.getPixels(), fBitmap.rowBytes(), ctable);
         return true;
     }
     return false;
@@ skipping 231 matching lines @@
         paint.getRasterizer() ||
         paint.getPathEffect() ||
         paint.isFakeBoldText() ||
         paint.getStyle() != SkPaint::kFill_Style ||
         !SkXfermode::IsMode(paint.getXfermode(), SkXfermode::kSrcOver_Mode))
     {
         return true;
     }
     return false;
 }