[Telemetry] Convert mp4 video to Timestamp+Bitmaps.

tools/telemetry/telemetry/core/bitmap_unittest.py

 # Copyright 2013 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.
 
+import tempfile
+import os
 import unittest
-import os
 
 from telemetry.core import bitmap
 from telemetry.core import util
 
 
 # This is a simple base64 encoded 2x2 PNG which contains, in order, a single
 # Red, Yellow, Blue, and Green pixel.
 test_png = """
 iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91
 JpzAAAAAXNSR0IArs4c6QAAAAlwSFlzAAALEwAACx
@@ skipping 11 matching lines @@
     bmp = bitmap.Bitmap.FromBase64Png(test_png)
 
     self.assertEquals(2, bmp.width)
     self.assertEquals(2, bmp.height)
 
     bmp.GetPixelColor(0, 0).AssertIsRGB(255, 0, 0)
     bmp.GetPixelColor(1, 1).AssertIsRGB(0, 255, 0)
     bmp.GetPixelColor(0, 1).AssertIsRGB(0, 0, 255)
     bmp.GetPixelColor(1, 0).AssertIsRGB(255, 255, 0)
 
-  def testReadFromPnfFile(self):
+  def testReadFromPngFile(self):
     file_bmp = bitmap.Bitmap.FromPngFile(test_png_path)
 
     self.assertEquals(2, file_bmp.width)
     self.assertEquals(2, file_bmp.height)
 
     file_bmp.GetPixelColor(0, 0).AssertIsRGB(255, 0, 0)
     file_bmp.GetPixelColor(1, 1).AssertIsRGB(0, 255, 0)
     file_bmp.GetPixelColor(0, 1).AssertIsRGB(0, 0, 255)
     file_bmp.GetPixelColor(1, 0).AssertIsRGB(255, 255, 0)
 
+  def testWritePngFile(self):
+    orig = bitmap.Bitmap.FromPngFile(test_png_path)
+    temp_file = tempfile.NamedTemporaryFile().name
+    orig.WritePngFile(temp_file)
+    new_file = bitmap.Bitmap.FromPngFile(temp_file)
+    self.assertTrue(orig.IsEqual(new_file))
+
   def testIsEqual(self):
     bmp = bitmap.Bitmap.FromBase64Png(test_png)
     file_bmp = bitmap.Bitmap.FromPngFile(test_png_path)
     self.assertTrue(bmp.IsEqual(file_bmp))
 
   def testDiff(self):
     file_bmp = bitmap.Bitmap.FromPngFile(test_png_path)
     file_bmp_2 = bitmap.Bitmap.FromPngFile(test_png_2_path)
 
     diff_bmp = file_bmp.Diff(file_bmp)
@@ skipping 14 matching lines @@
     diff_bmp.GetPixelColor(0, 0).AssertIsRGB(0, 255, 255)
     diff_bmp.GetPixelColor(1, 1).AssertIsRGB(255, 0, 255)
     diff_bmp.GetPixelColor(0, 1).AssertIsRGB(255, 255, 0)
     diff_bmp.GetPixelColor(1, 0).AssertIsRGB(0, 0, 255)
 
     diff_bmp.GetPixelColor(0, 2).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(1, 2).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 0).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 1).AssertIsRGB(255, 255, 255)
     diff_bmp.GetPixelColor(2, 2).AssertIsRGB(255, 255, 255)