From 210b1880366f4727616ee0d3232994236f62b9df Mon Sep 17 00:00:00 2001
From: Ralph Giles <giles@mozilla.com>
Date: Tue, 28 May 2013 13:55:00 -0700
Subject: [PATCH] Bug 875305 - Replace slow webvtt caption selectors with
 classes. r=bz

We set the class caption-box class on the anonymous div which
acts as the parent container for the captions overlayed on
the video frame.

caption-text isn't currently used, but will be applied to
child elements by when bug 833382 lands.
---
 layout/generic/nsVideoFrame.cpp | 3 +++
 layout/style/html.css           | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/layout/generic/nsVideoFrame.cpp b/layout/generic/nsVideoFrame.cpp
index 9bf807d85094..778062f09cd6 100644
--- a/layout/generic/nsVideoFrame.cpp
+++ b/layout/generic/nsVideoFrame.cpp
@@ -17,6 +17,7 @@
 #include "nsIDOMHTMLImageElement.h"
 #include "nsIDOMHTMLElement.h"
 #include "nsDisplayList.h"
+#include "nsGenericHTMLElement.h"
 #include "gfxContext.h"
 #include "gfxImageSurface.h"
 #include "nsPresContext.h"
@@ -111,6 +112,8 @@ nsVideoFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
     NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
     mCaptionDiv = NS_NewHTMLDivElement(nodeInfo.forget());
     NS_ENSURE_TRUE(mCaptionDiv, NS_ERROR_OUT_OF_MEMORY);
+    nsGenericHTMLElement* div = static_cast<nsGenericHTMLElement*>(mCaptionDiv.get());
+    div->SetClassName(NS_LITERAL_STRING("caption-box"));
 
     if (!aElements.AppendElement(mCaptionDiv))
       return NS_ERROR_OUT_OF_MEMORY;
diff --git a/layout/style/html.css b/layout/style/html.css
index 9775ebaf084c..063c6fac4358 100644
--- a/layout/style/html.css
+++ b/layout/style/html.css
@@ -726,14 +726,14 @@ audio:not([controls]) {
   -moz-transform: translate(0) !important;
 }
 
-video > div {
+video > .caption-box {
   text-align: center;
   font-weight: bold;
   font-size: 24px;
   pointer-events: none;
 }
 
-video > div p {
+video > div .caption-text {
   color: gold;
   background-color: rgba(105,105,105,0.4);
   pointer-events: auto;