Add video metrics integration test

tools/chrome_proxy/webdriver/video.py

Index: tools/chrome_proxy/webdriver/video.py
diff --git a/tools/chrome_proxy/webdriver/video.py b/tools/chrome_proxy/webdriver/video.py
index 9755e045fe301cdb0a298feb976dca399dfbb03f..321d404e8d8bd1d05a0a135653113b348630756a 100644
--- a/tools/chrome_proxy/webdriver/video.py
+++ b/tools/chrome_proxy/webdriver/video.py
@@ -42,6 +42,36 @@ class Video(IntegrationTest):
           self.assertHasChromeProxyViaHeader(response)
       self.assertTrue(saw_video_response, 'No video request seen in test!')
 
+  # Check the compressed video has the same frame count, width, height, and
+  # duration as uncompressed.
+  def testVideoMetrics(self):
+    expected = {
+      'duration': 60.127,

[Tom Bergan, 2017/02/17 18:20:48]

I haven't done the math, but at first glance, this number looks like it might
not be precisely representable in 64-bit floating point. That means this
comparison is subject to imprecision. Suggest using an approximate comparison of
+/- 0.25s ?

[Robert Ogden, 2017/02/17 18:49:28]

Done.

[RyanSturm, 2017/02/17 19:24:10]

As a nit on a nit, delta=0.25 is way, way bigger than any float round-off we'd
get here. I would take .25 off as a noticeable issue that could rear it's head
as the audio being out of sync by .25 seconds. Can you just make it a
millisecond.

[Robert Ogden, 2017/02/17 19:28:18]

Done.

+      'webkitDecodedFrameCount': 1080.0,
+      'videoWidth': 640.0,
+      'videoHeight': 360.0
+    }
+    with TestDriver() as t:
+      t.AddChromeArg('--enable-spdy-proxy-auth')
+      t.LoadURL('http://check.googlezip.net/cacheable/video/buck_bunny_640x360_24fps_video.html')
+      # Check request vwas proxied and we got a compressed video back.
+      for response in t.GetHTTPResponses():
+        self.assertHasChromeProxyViaHeader(response)
+        if ('content-type' in response.response_headers
+            and 'video' in response.response_headers['content-type']):
+          self.assertEqual('video/webm',
+            response.response_headers['content-type'])
+      t.ExecuteJavascriptStatement('document.getElementById("video").play()')
+      # Wait for the video to finish playing, plus some headroom.
+      time.sleep(80)
+      # Check each metric against its expected value.
+      for metric in expected:
+        actual = float(t.ExecuteJavascriptStatement(
+          'document.getElementById("video").%s' % metric))
+        self.assertEqual(expected[metric], actual, "Compressed video metric "
+          "doesn't match expected! Metric=%s Expected=%f Actual=%f"
+          % (metric, expected[metric], actual))
+
   # Check the frames of a compressed video.
   def testVideoFrames(self):
     self.instrumentedVideoTest('http://check.googlezip.net/cacheable/video/buck_bunny_640x360_24fps_video.html')