Add skia::RefPtr class to wrap ref counted classes from Skia.

skia/ext/bitmap_platform_device_win.cc

Index: skia/ext/bitmap_platform_device_win.cc
diff --git a/skia/ext/bitmap_platform_device_win.cc b/skia/ext/bitmap_platform_device_win.cc
index 4e5bbce33895aeb93d23483bef9504f6d74add68..d72955617adb712011972bcd8aca92bff9ec5af2 100644
--- a/skia/ext/bitmap_platform_device_win.cc
+++ b/skia/ext/bitmap_platform_device_win.cc
@@ -177,7 +177,6 @@ BitmapPlatformDevice::BitmapPlatformDevice(
 
 BitmapPlatformDevice::~BitmapPlatformDevice() {
   SkASSERT(begin_paint_count_ == 0);
-  data_->unref();
 }
 
 HDC BitmapPlatformDevice::BeginPlatformPaint() {
@@ -272,10 +271,10 @@ SkCanvas* CreatePlatformCanvas(int width,
                                bool is_opaque,
                                HANDLE shared_section,
                                OnFailureType failureType) {
-  SkDevice* dev = BitmapPlatformDevice::Create(width,
-                                               height,
-                                               is_opaque,
-                                               shared_section);
+  skia::RefPtr<SkDevice> dev = BitmapPlatformDevice::Create(width,
+                                                            height,
+                                                            is_opaque,
+                                                            shared_section);
   return CreateCanvas(dev, failureType);
 }