1 files changed, 125 insertions, 0 deletions
diff --git a/mobile/android/components/ImageBlockingPolicy.js b/mobile/android/components/ImageBlockingPolicy.js
new file mode 100644
index 000000000..2444bda06
--- /dev/null
+++ b/mobile/android/components/ImageBlockingPolicy.js
@@ -0,0 +1,125 @@
+/* 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/. */
+
+const { classes: Cc, interfaces: Ci, manager: Cm, utils: Cu, results: Cr } = Components;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Timer.jsm");
+
+////////////////////////////////////////////////////////////////////////////////
+//// Constants
+
+//// SVG placeholder image for blocked image content
+const PLACEHOLDER_IMG = "chrome://browser/skin/images/placeholder_image.svg";
+
+//// Telemetry
+const TELEMETRY_TAP_TO_LOAD_ENABLED = "TAP_TO_LOAD_ENABLED";
+const TELEMETRY_SHOW_IMAGE_SIZE = "TAP_TO_LOAD_IMAGE_SIZE";
+const TOPIC_GATHER_TELEMETRY = "gather-telemetry";
+
+//// Gecko preference
+const PREF_IMAGEBLOCKING = "browser.image_blocking";
+
+//// Enabled options
+const OPTION_NEVER = 0;
+const OPTION_ALWAYS = 1;
+const OPTION_WIFI_ONLY = 2;
+
+
+/**
+ * Content policy for blocking images
+ */
+function ImageBlockingPolicy() {
+  Services.obs.addObserver(this, TOPIC_GATHER_TELEMETRY, false);
+}
+
+ImageBlockingPolicy.prototype = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIContentPolicy, Ci.nsIObserver]),
+  classDescription: "Click-To-Play Image",
+  classID: Components.ID("{f55f77f9-d33d-4759-82fc-60db3ee0bb91}"),
+  contractID: "@mozilla.org/browser/blockimages-policy;1",
+  xpcom_categories: [{category: "content-policy", service: true}],
+
+  // nsIContentPolicy interface implementation
+  shouldLoad: function(contentType, contentLocation, requestOrigin, node, mimeTypeGuess, extra) {
+    // When enabled or when on cellular, and option for cellular-only is selected
+    if (this._enabled() == OPTION_NEVER || (this._enabled() == OPTION_WIFI_ONLY && this._usingCellular())) {
+      if (contentType === Ci.nsIContentPolicy.TYPE_IMAGE || contentType === Ci.nsIContentPolicy.TYPE_IMAGESET) {
+        // Accept any non-http(s) image URLs
+        if (!contentLocation.schemeIs("http") && !contentLocation.schemeIs("https")) {
+          return Ci.nsIContentPolicy.ACCEPT;
+        }
+
+        if (node instanceof Ci.nsIDOMHTMLImageElement) {
+          // Accept if the user has asked to view the image
+          if (node.getAttribute("data-ctv-show") == "true") {
+            sendImageSizeTelemetry(node.getAttribute("data-ctv-src"));
+            return Ci.nsIContentPolicy.ACCEPT;
+          }
+
+          setTimeout(() => {
+            // Cache the original image URL and swap in our placeholder
+            node.setAttribute("data-ctv-src", contentLocation.spec);
+            node.setAttribute("src", PLACEHOLDER_IMG);
+
+            // For imageset (img + srcset) the "srcset" is used even after we reset the "src" causing a loop.
+            // We are given the final image URL anyway, so it's OK to just remove the "srcset" value.
+            node.removeAttribute("srcset");
+          }, 0);
+        }
+
+        // Reject any image that is not associated with a DOM element
+        return Ci.nsIContentPolicy.REJECT;
+      }
+    }
+
+    // Accept all other content types
+    return Ci.nsIContentPolicy.ACCEPT;
+  },
+
+  shouldProcess: function(contentType, contentLocation, requestOrigin, node, mimeTypeGuess, extra) {
+    return Ci.nsIContentPolicy.ACCEPT;
+  },
+
+  _usingCellular: function() {
+    let network = Cc["@mozilla.org/network/network-link-service;1"].getService(Ci.nsINetworkLinkService);
+    return !(network.linkType == Ci.nsINetworkLinkService.LINK_TYPE_UNKNOWN ||
+        network.linkType == Ci.nsINetworkLinkService.LINK_TYPE_ETHERNET ||
+        network.linkType == Ci.nsINetworkLinkService.LINK_TYPE_USB  ||
+        network.linkType == Ci.nsINetworkLinkService.LINK_TYPE_WIFI);
+  },
+
+  _enabled: function() {
+    return Services.prefs.getIntPref(PREF_IMAGEBLOCKING);
+  },
+
+  observe : function (subject, topic, data) {
+    if (topic == TOPIC_GATHER_TELEMETRY) {
+      Services.telemetry.getHistogramById(TELEMETRY_TAP_TO_LOAD_ENABLED).add(this._enabled());
+    }
+  },
+};
+
+function sendImageSizeTelemetry(imageURL) {
+  let xhr = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIXMLHttpRequest);
+  xhr.open("HEAD", imageURL, true);
+  xhr.onreadystatechange = function (e) {
+    if (xhr.readyState != 4) {
+      return;
+    }
+    if (xhr.status != 200) {
+      return;
+    }
+    let contentLength = xhr.getResponseHeader("Content-Length");
+    if (!contentLength) {
+      return;
+    }
+    let imageSize = contentLength / 1024;
+    Services.telemetry.getHistogramById(TELEMETRY_SHOW_IMAGE_SIZE).add(imageSize);
+  };
+  xhr.send(null);
+}
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([ImageBlockingPolicy]);