Add pixel-by-pixel comparison tests for play/pause controls in PiP. Modify the...

Add pixel-by-pixel comparison tests for play/pause controls in PiP. Modify the pixel comparison function to use an actual (expected) image instead of just RGB values.

Change-Id: I1604df59d390a460fe5a0200cbae273bdd60e023
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574451
Auto-Submit: Clifford Cheng <cliffordcheng@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Clifford Cheng <cliffordcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663880}

chrome/test/data/media/picture-in-picture/pixel_test.html

@@ -26,5 +26,16 @@
       window.domAutomationController.send(false);
     });
   }
+
+  function changeVideoSrc() {
+    if (video.srcObject) {
+      video.srcObject.getTracks().forEach(track => track.stop());
+      video.srcObject = null;
+    }
+    video.src = 'pixel_test_video.webm';
+    video.play()
+    .then(_ => { window.domAutomationController.send(true); })
+    .catch(e => { window.domAutomationController.send(false); });
+  }
 </script>
 </html>