--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -678,19 +678,16 @@
 ; Services (gre) prefs
 @RESPATH@/defaults/pref/services-sync.js
 
 ; [Layout Engine Resources]
 ; Style Sheets, Graphics and other Resources used by the layout engine.
 @RESPATH@/res/EditorOverride.css
 @RESPATH@/res/contenteditable.css
 @RESPATH@/res/designmode.css
-@RESPATH@/res/ImageDocument.css
-@RESPATH@/res/TopLevelImageDocument.css
-@RESPATH@/res/TopLevelVideoDocument.css
 @RESPATH@/res/table-add-column-after-active.gif
 @RESPATH@/res/table-add-column-after-hover.gif
 @RESPATH@/res/table-add-column-after.gif
 @RESPATH@/res/table-add-column-before-active.gif
 @RESPATH@/res/table-add-column-before-hover.gif
 @RESPATH@/res/table-add-column-before.gif
 @RESPATH@/res/table-add-row-after-active.gif
 @RESPATH@/res/table-add-row-after-hover.gif
@@ -711,16 +708,19 @@
 @RESPATH@/res/fonts/*
 @RESPATH@/res/dtd/*
 @RESPATH@/res/html/*
 @RESPATH@/res/language.properties
 #ifdef XP_MACOSX
 @RESPATH@/res/MainMenu.nib/
 #endif
 
+; Content-accessible resources.
+@RESPATH@/contentaccessible/*
+
 ; svg
 @RESPATH@/res/svg.css
 @RESPATH@/components/dom_svg.xpt
 @RESPATH@/components/dom_smil.xpt
 
 ; [Personal Security Manager]
 ;
 ; NSS libraries are signed in the staging directory,

--- a/devtools/client/jsonview/converter-child.js
+++ b/devtools/client/jsonview/converter-child.js
@@ -203,17 +203,17 @@ function initialHTML(doc) {
   } else if (platform.startsWith("Darwin")) {
     os = "mac";
   } else {
     os = "linux";
   }
 
   // The base URI is prepended to all URIs instead of using a <base> element
   // because the latter can be blocked by a CSP base-uri directive (bug 1316393)
-  let baseURI = "resource://devtools/client/jsonview/";
+  let baseURI = "resource://devtools-client-jsonview/";
 
   let style = doc.createElement("link");
   style.rel = "stylesheet";
   style.type = "text/css";
   style.href = baseURI + "css/main.css";
 
   let script = doc.createElement("script");
   script.src = baseURI + "lib/require.js";

--- a/devtools/client/jsonview/viewer-config.js
+++ b/devtools/client/jsonview/viewer-config.js
@@ -16,21 +16,21 @@
  * In order to use the developer version you need to specify the following
  * in your .mozconfig (see also bug 1181646):
  * ac_add_options --enable-debug-js-modules
  *
  * React module ID is using exactly the same (relative) path as the rest
  * of the code base, so it's consistent and modules can be easily reused.
  */
 require.config({
-  baseUrl: "resource://devtools/client/jsonview/",
+  baseUrl: "resource://devtools-client-jsonview/",
   paths: {
-    "devtools/client/shared": "resource://devtools/client/shared",
+    "devtools/client/shared": "resource://devtools-client-shared",
     "devtools/shared": "resource://devtools/shared",
     "devtools/client/shared/vendor/react":
       JSONView.debug
-      ? "resource://devtools/client/shared/vendor/react-dev"
-      : "resource://devtools/client/shared/vendor/react"
+      ? "resource://devtools-client-shared/vendor/react-dev"
+      : "resource://devtools-client-shared/vendor/react"
   }
 });
 
 // Load the main panel module
 requirejs(["json-viewer"]);

--- a/devtools/shared/jar.mn
+++ b/devtools/shared/jar.mn
@@ -1,10 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 devtools.jar:
 %   resource devtools %modules/devtools/
+%   resource devtools-client-jsonview resource://devtools/client/jsonview/ contentaccessible=yes
+%   resource devtools-client-shared resource://devtools/client/shared/ contentaccessible=yes
 # The typical approach would be to list all the resource files in this manifest
 # for installation.  Instead of doing this, use the DevToolsModules syntax via
 # moz.build files to do the installation so that we can enforce correct paths
 # based on source tree location.

--- a/dom/html/ImageDocument.cpp
+++ b/dom/html/ImageDocument.cpp
@@ -274,19 +274,19 @@ ImageDocument::SetScriptGlobalObject(nsI
       target->AddEventListener(NS_LITERAL_STRING("click"), this, false);
     }
 
     target = do_QueryInterface(aScriptGlobalObject);
     target->AddEventListener(NS_LITERAL_STRING("resize"), this, false);
     target->AddEventListener(NS_LITERAL_STRING("keypress"), this, false);
 
     if (GetReadyStateEnum() != nsIDocument::READYSTATE_COMPLETE) {
-      LinkStylesheet(NS_LITERAL_STRING("resource://gre/res/ImageDocument.css"));
+      LinkStylesheet(NS_LITERAL_STRING("resource://content-accessible/ImageDocument.css"));
       if (!nsContentUtils::IsChildOfSameType(this)) {
-        LinkStylesheet(NS_LITERAL_STRING("resource://gre/res/TopLevelImageDocument.css"));
+        LinkStylesheet(NS_LITERAL_STRING("resource://content-accessible/TopLevelImageDocument.css"));
         LinkStylesheet(NS_LITERAL_STRING("chrome://global/skin/media/TopLevelImageDocument.css"));
       }
     }
     BecomeInteractive();
   }
 }
 
 void

--- a/dom/html/VideoDocument.cpp
+++ b/dom/html/VideoDocument.cpp
@@ -69,17 +69,17 @@ VideoDocument::SetScriptGlobalObject(nsI
 {
   // Set the script global object on the superclass before doing
   // anything that might require it....
   MediaDocument::SetScriptGlobalObject(aScriptGlobalObject);
 
   if (aScriptGlobalObject) {
     if (!nsContentUtils::IsChildOfSameType(this) &&
         GetReadyStateEnum() != nsIDocument::READYSTATE_COMPLETE) {
-      LinkStylesheet(NS_LITERAL_STRING("resource://gre/res/TopLevelVideoDocument.css"));
+      LinkStylesheet(NS_LITERAL_STRING("resource://content-accessible/TopLevelVideoDocument.css"));
       LinkStylesheet(NS_LITERAL_STRING("chrome://global/skin/media/TopLevelVideoDocument.css"));
       LinkScript(NS_LITERAL_STRING("chrome://global/content/TopLevelVideoDocument.js"));
     }
     BecomeInteractive();
   }
 }
 
 nsresult

--- a/dom/xml/resources/XMLPrettyPrint.css
+++ b/dom/xml/resources/XMLPrettyPrint.css
@@ -1,14 +1,14 @@
 @charset "UTF-8";
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-@import url("resource://gre-resources/viewsource.css");
+@import url("resource://content-accessible/viewsource.css");
 
 #header {
   background-color: #ccc;
   border-bottom: 3px solid black;
   padding: 0.5em;
   margin-bottom: 1em;
 }
 

--- a/layout/style/jar.mn
+++ b/layout/style/jar.mn
@@ -2,17 +2,16 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 toolkit.jar:
 *  res/ua.css                                (res/ua.css)
 *  res/html.css                              (res/html.css)
    res/quirk.css                             (res/quirk.css)
    res/plaintext.css                         (res/plaintext.css)
-   res/viewsource.css                        (res/viewsource.css)
    res/counterstyles.css                     (res/counterstyles.css)
    res/noscript.css                          (res/noscript.css)
    res/noframes.css                          (res/noframes.css)
 *  res/forms.css                             (res/forms.css)
    res/number-control.css                    (res/number-control.css)
    res/arrow.gif                             (res/arrow.gif)
    res/arrow-left.gif                        (res/arrow-left.gif)
    res/arrow-right.gif                       (res/arrow-right.gif)
@@ -28,8 +27,9 @@ toolkit.jar:
    res/accessiblecaret-tilt-left@2x.png      (res/accessiblecaret-tilt-left@2x.png)
    res/accessiblecaret-tilt-left@2.25x.png   (res/accessiblecaret-tilt-left@2.25x.png)
    res/accessiblecaret-tilt-right@1x.png     (res/accessiblecaret-tilt-right@1x.png)
    res/accessiblecaret-tilt-right@1.5x.png   (res/accessiblecaret-tilt-right@1.5x.png)
    res/accessiblecaret-tilt-right@2x.png     (res/accessiblecaret-tilt-right@2x.png)
    res/accessiblecaret-tilt-right@2.25x.png  (res/accessiblecaret-tilt-right@2.25x.png)
 
 % resource gre-resources %res/
+% resource content-accessible resource://gre/contentaccessible/ contentaccessible=yes

--- a/layout/style/moz.build
+++ b/layout/style/moz.build
@@ -295,17 +295,21 @@ LOCAL_INCLUDES += [
     '/image',
 ]
 
 JAR_MANIFESTS += ['jar.mn']
 
 RESOURCE_FILES += [
     'contenteditable.css',
     'designmode.css',
+]
+
+CONTENT_ACCESSIBLE_FILES += [
     'ImageDocument.css',
+    'res/viewsource.css',
     'TopLevelImageDocument.css',
     'TopLevelVideoDocument.css',
 ]
 
 GENERATED_FILES += [
     'nsStyleStructList.h',
 ]
 

--- a/mobile/android/installer/package-manifest.in
+++ b/mobile/android/installer/package-manifest.in
@@ -454,18 +454,16 @@
 @BINPATH@/greprefs.js
 @BINPATH@/defaults/autoconfig/prefcalls.js
 
 ; [Layout Engine Resources]
 ; Style Sheets, Graphics and other Resources used by the layout engine.
 @BINPATH@/res/EditorOverride.css
 @BINPATH@/res/contenteditable.css
 @BINPATH@/res/designmode.css
-@BINPATH@/res/TopLevelImageDocument.css
-@BINPATH@/res/TopLevelVideoDocument.css
 @BINPATH@/res/table-add-column-after-active.gif
 @BINPATH@/res/table-add-column-after-hover.gif
 @BINPATH@/res/table-add-column-after.gif
 @BINPATH@/res/table-add-column-before-active.gif
 @BINPATH@/res/table-add-column-before-hover.gif
 @BINPATH@/res/table-add-column-before.gif
 @BINPATH@/res/table-add-row-after-active.gif
 @BINPATH@/res/table-add-row-after-hover.gif
@@ -485,16 +483,19 @@
 @BINPATH@/res/language.properties
 
 #ifndef MOZ_ANDROID_EXCLUDE_FONTS
 @BINPATH@/res/fonts/*
 #else
 @BINPATH@/res/fonts/*.properties
 #endif
 
+; Content-accessible resources.
+@BINPATH@/contentaccessible/*
+
 ; svg
 @BINPATH@/res/svg.css
 @BINPATH@/components/dom_svg.xpt
 @BINPATH@/components/dom_smil.xpt
 
 ; [Personal Security Manager]
 ;
 @BINPATH@/components/pipnss.xpt

--- a/parser/html/nsHtml5ViewSourceUtils.cpp
+++ b/parser/html/nsHtml5ViewSourceUtils.cpp
@@ -45,12 +45,12 @@ nsHtml5HtmlAttributes*
 nsHtml5ViewSourceUtils::NewLinkAttributes()
 {
   nsHtml5HtmlAttributes* linkAttrs = new nsHtml5HtmlAttributes(0);
   nsHtml5String rel = nsHtml5Portability::newStringFromLiteral("stylesheet");
   linkAttrs->addAttribute(nsHtml5AttributeName::ATTR_REL, rel, -1);
   nsHtml5String type = nsHtml5Portability::newStringFromLiteral("text/css");
   linkAttrs->addAttribute(nsHtml5AttributeName::ATTR_TYPE, type, -1);
   nsHtml5String href = nsHtml5Portability::newStringFromLiteral(
-    "resource://gre-resources/viewsource.css");
+    "resource://content-accessible/viewsource.css");
   linkAttrs->addAttribute(nsHtml5AttributeName::ATTR_HREF, href, -1);
   return linkAttrs;
 }

--- a/python/mozbuild/mozbuild/frontend/context.py
+++ b/python/mozbuild/mozbuild/frontend/context.py
@@ -2085,16 +2085,24 @@ SPECIAL_VARIABLES = {
         subdirectory they should be exported to. For example, to export
         ``foo.res`` to the top-level directory, and ``bar.res`` to ``fonts/``,
         append to ``RESOURCE_FILES`` like so::
 
            RESOURCE_FILES += ['foo.res']
            RESOURCE_FILES.fonts += ['bar.res']
         """),
 
+    'CONTENT_ACCESSIBLE_FILES': (lambda context: context['FINAL_TARGET_FILES'].contentaccessible, list,
+        """List of files which can be accessed by web content through resource:// URIs.
+
+        ``CONTENT_ACCESSIBLE_FILES`` is used to list the files to be exported
+        to ``dist/bin/contentaccessible``. Files can also be appended to a
+        field to indicate which subdirectory they should be exported to.
+        """),
+
     'EXTRA_JS_MODULES': (lambda context: context['FINAL_TARGET_FILES'].modules, list,
         """Additional JavaScript files to distribute.
 
         This variable contains a list of files to copy into
         ``$(FINAL_TARGET)/modules.
         """),
 
     'EXTRA_PP_JS_MODULES': (lambda context: context['FINAL_TARGET_PP_FILES'].modules, list,

--- a/python/mozbuild/mozpack/chrome/manifest.py
+++ b/python/mozbuild/mozpack/chrome/manifest.py
@@ -33,16 +33,17 @@ class ManifestEntry(object):
         'application',
         'platformversion',
         'os',
         'osversion',
         'abi',
         'xpcnativewrappers',
         'tablet',
         'process',
+        'contentaccessible',
     ]
 
     def __init__(self, base, *flags):
         '''
         Initialize a manifest entry with the given base path and flags.
         '''
         self.base = base
         self.flags = Flags(*flags)

--- a/python/mozbuild/mozpack/packager/formats.py
+++ b/python/mozbuild/mozpack/packager/formats.py
@@ -335,9 +335,10 @@ class OmniJarSubFormatter(PiecemealForma
                 not (path[2] == 'channel-prefs.js' and
                      path[1] in ['pref', 'preferences'])
         return path[0] in [
             'modules',
             'greprefs.js',
             'hyphenation',
             'localization',
             'update.locale',
+            'contentaccessible',
         ]

--- a/toolkit/content/browser-content.js
+++ b/toolkit/content/browser-content.js
@@ -1335,17 +1335,17 @@ var ViewSelectionSource = {
     var topNode = this._targetNode;
     while (topNode && topNode.localName != topTag) {
       topNode = topNode.parentNode;
     }
     if (!topNode)
       return undefined;
 
     // serialize
-    const VIEW_SOURCE_CSS = "resource://gre-resources/viewsource.css";
+    const VIEW_SOURCE_CSS = "resource://content-accessible/viewsource.css";
     const BUNDLE_URL = "chrome://global/locale/viewSource.properties";
 
     let bundle = Services.strings.createBundle(BUNDLE_URL);
     var title = bundle.GetStringFromName("viewMathMLSourceTitle");
     var wrapClass = this.wrapLongLines ? ' class="wrap"' : "";
     var source =
       "<!DOCTYPE html>"
     + "<html>"