Update from https://crrev.com/306706

skia/ext/bitmap_platform_device_mac.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "skia/ext/bitmap_platform_device_mac.h"
 
 #import <ApplicationServices/ApplicationServices.h>
 #include <time.h>
 
 #include "base/mac/mac_util.h"
@@ skipping 78 matching lines @@
 }
 
 
 // We use this static factory function instead of the regular constructor so
 // that we can create the pixel data before calling the constructor. This is
 // required so that we can call the base class' constructor with the pixel
 // data.
 BitmapPlatformDevice* BitmapPlatformDevice::Create(CGContextRef context,
                                                    int width,
                                                    int height,
-                                                   bool is_opaque) {
+                                                   bool is_opaque,
+                                                   bool do_clear) {
   if (RasterDeviceTooBigToAllocate(width, height))
     return NULL;
 
   SkBitmap bitmap;
   // TODO: verify that the CG Context's pixels will have tight rowbytes or pass in the correct
   // rowbytes for the case when context != NULL.
   bitmap.setInfo(SkImageInfo::MakeN32(width, height, is_opaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType));
 
   void* data;
   if (context) {
     data = CGBitmapContextGetData(context);
     bitmap.setPixels(data);
   } else {
     if (!bitmap.tryAllocPixels())
       return NULL;
     data = bitmap.getPixels();
   }
+  if (do_clear)
+    memset(data, 0, bitmap.getSafeSize());
 
   // If we were given data, then don't clobber it!
 #ifndef NDEBUG
   if (!context && is_opaque) {
     // To aid in finding bugs, we set the background color to something
     // obviously wrong so it will be noticable when it is not cleared
     bitmap.eraseARGB(255, 0, 255, 128);  // bright bluish green
   }
 #endif
 
   if (!context) {
     context = CGContextForData(data, width, height);
     if (!context)
       return NULL;
   } else
     CGContextRetain(context);
 
   BitmapPlatformDevice* rv = new BitmapPlatformDevice(context, bitmap);
 
   // The device object took ownership of the graphics context with its own
   // CGContextRetain call.
   CGContextRelease(context);
 
   return rv;
 }
 
-BitmapPlatformDevice* BitmapPlatformDevice::CreateAndClear(int width,
-                                                           int height,
-                                                           bool is_opaque) {
-  BitmapPlatformDevice* device = Create(NULL, width, height, is_opaque);
-  if (!is_opaque)
-    device->clear(0);
-  return device;
-}
-
 BitmapPlatformDevice* BitmapPlatformDevice::CreateWithData(uint8_t* data,
                                                            int width,
                                                            int height,
                                                            bool is_opaque) {
   CGContextRef context = NULL;
   if (data)
     context = CGContextForData(data, width, height);
 
-  BitmapPlatformDevice* rv = Create(context, width, height, is_opaque);
+  BitmapPlatformDevice* rv = Create(context, width, height, is_opaque, false);
 
   // The device object took ownership of the graphics context with its own
   // CGContextRetain call.
   if (context)
     CGContextRelease(context);
 
   return rv;
 }
 
 // The device will own the bitmap, which corresponds to also owning the pixel
@@ skipping 60 matching lines @@
     bounds.size.height = height();
     CGContextDrawImage(context, bounds, image);
   }
   CGImageRelease(image);
 
   if (created_dc)
     ReleaseBitmapContext();
 }
 
 SkBaseDevice* BitmapPlatformDevice::onCreateCompatibleDevice(
-                                                     const CreateInfo& info) {
-  SkASSERT(info.fInfo.colorType() == kN32_SkColorType);
-  return BitmapPlatformDevice::CreateAndClear(info.fInfo.width(),
-                                              info.fInfo.height(),
-                                              info.fInfo.isOpaque());
+                                                     const CreateInfo& cinfo) {
+  const SkImageInfo& info = cinfo.fInfo;
+  const bool do_clear = !info.isOpaque();
+  SkASSERT(info.colorType() == kN32_SkColorType);
+  return Create(NULL, info.width(), info.height(), info.isOpaque(), do_clear);
 }
 
 // PlatformCanvas impl
 
 SkCanvas* CreatePlatformCanvas(CGContextRef ctx, int width, int height,
                                bool is_opaque, OnFailureType failureType) {
+  const bool do_clear = false;
   skia::RefPtr<SkBaseDevice> dev = skia::AdoptRef(
-      BitmapPlatformDevice::Create(ctx, width, height, is_opaque));
+      BitmapPlatformDevice::Create(ctx, width, height, is_opaque, do_clear));
   return CreateCanvas(dev, failureType);
 }
 
 SkCanvas* CreatePlatformCanvas(int width, int height, bool is_opaque,
                                uint8_t* data, OnFailureType failureType) {
   skia::RefPtr<SkBaseDevice> dev = skia::AdoptRef(
       BitmapPlatformDevice::CreateWithData(data, width, height, is_opaque));
   return CreateCanvas(dev, failureType);
 }
 
@@ skipping 13 matching lines @@
 
   if (!is_opaque)
     bitmap_.eraseColor(0);
 
   surface_ = CGContextForData(bitmap_.getPixels(), bitmap_.width(),
                               bitmap_.height());
   return true;
 }
 
 }  // namespace skia