Optionally clear PlatformCanvas instances.

skia/ext/bitmap_platform_device_linux.cc

Index: skia/ext/bitmap_platform_device_linux.cc
===================================================================
--- skia/ext/bitmap_platform_device_linux.cc	(revision 127021)
+++ skia/ext/bitmap_platform_device_linux.cc	(working copy)
@@ -110,6 +110,14 @@
   return device;
 }
 
+BitmapPlatformDevice* BitmapPlatformDevice::CreateAndClear(int width,
+                                                           int height,
+                                                           bool is_opaque) {
+  // The Linux port always constructs initialized bitmaps, so there is no extra
+  // work to perform here.
+  return Create(width, height, is_opaque);
+}
+
 BitmapPlatformDevice* BitmapPlatformDevice::Create(int width, int height,
                                                    bool is_opaque,
                                                    uint8_t* data) {