This Cairo-specific function has no callers and no tests. Comments

indicate that other backends need equivalent functions, but they
seem instead to just take an extra parameter to Create().

Review URL: https://codereview.chromium.org/1413993006

Cr-Commit-Position: refs/heads/master@{#357124}

skia/ext/bitmap_platform_device_cairo.cc

@@ -136,14 +136,6 @@ BitmapPlatformDevice* BitmapPlatformDevice::Create(int width, int height,
   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) {

skia/ext/bitmap_platform_device_cairo.h

@@ -72,12 +72,6 @@ class BitmapPlatformDevice : public SkBitmapDevice, public PlatformDevice {
   // completely opaque and allows some optimizations.
   static BitmapPlatformDevice* Create(int width, int height, bool is_opaque);
 
-  // Performs the same construction as Create.
-  // Other ports require a separate construction routine because Create does not
-  // initialize the bitmap to 0.
-  static BitmapPlatformDevice* CreateAndClear(int width, int height,
-                                              bool is_opaque);
-
   // This doesn't take ownership of |data|. If |data| is NULL, the contents
   // of the device are initialized to 0.
   static BitmapPlatformDevice* Create(int width, int height, bool is_opaque,