--- a/devtools/client/netmonitor/src/components/StatisticsPanel.js
+++ b/devtools/client/netmonitor/src/components/StatisticsPanel.js
@@ -203,29 +203,26 @@ class StatisticsPanel extends Component 
         // "fonts"
         type = 4;
       } else if (Filters.images(request)) {
         // "images"
         type = 5;
       } else if (Filters.media(request)) {
         // "media"
         type = 6;
-      } else if (Filters.flash(request)) {
-        // "flash"
-        type = 7;
       } else if (Filters.ws(request)) {
         // "ws"
-        type = 8;
+        type = 7;
       } else if (Filters.xhr(request)) {
         // Verify XHR last, to categorize other mime types in their own blobs.
         // "xhr"
         type = 3;
       } else {
         // "other"
-        type = 9;
+        type = 8;
       }
 
       if (emptyCache || !this.responseIsFresh(request)) {
         data[type].time += request.totalTime || 0;
         data[type].size += request.contentSize || 0;
         data[type].transferredSize += request.transferredSize || 0;
       } else {
         data[type].cached++;

--- a/devtools/client/netmonitor/src/constants.js
+++ b/devtools/client/netmonitor/src/constants.js
@@ -270,17 +270,16 @@ const FILTER_FLAGS = [
 const FILTER_TAGS = [
   "html",
   "css",
   "js",
   "xhr",
   "fonts",
   "images",
   "media",
-  "flash",
   "ws",
   "other",
 ];
 
 const REQUESTS_WATERFALL = {
   BACKGROUND_TICKS_MULTIPLE: 5, // ms
   BACKGROUND_TICKS_SCALES: 3,
   BACKGROUND_TICKS_SPACING_MIN: 10, // px

--- a/devtools/client/netmonitor/src/utils/filter-predicates.js
+++ b/devtools/client/netmonitor/src/utils/filter-predicates.js
@@ -56,25 +56,16 @@ function isImage({ mimeType }) {
 function isMedia({ mimeType }) {
   // Not including images.
   return mimeType && (
     mimeType.includes("audio/") ||
     mimeType.includes("video/") ||
     mimeType.includes("model/"));
 }
 
-function isFlash({ url, mimeType }) {
-  // Flash is a mess.
-  return (mimeType && (
-      mimeType.includes("/x-flv") ||
-      mimeType.includes("/x-shockwave-flash"))) ||
-    url.includes(".swf") ||
-    url.includes(".flv");
-}
-
 function isWS({ requestHeaders, responseHeaders }) {
   // Detect a websocket upgrade if request has an Upgrade header with value 'websocket'
   if (!requestHeaders || !Array.isArray(requestHeaders.headers)) {
     return false;
   }
 
   // Find the 'upgrade' header.
   let upgradeHeader = requestHeaders.headers.find(header => {
@@ -95,28 +86,27 @@ function isWS({ requestHeaders, response
   if (!upgradeHeader || upgradeHeader.value != "websocket") {
     return false;
   }
 
   return true;
 }
 
 function isOther(item) {
-  let tests = [isHtml, isCss, isJs, isXHR, isFont, isImage, isMedia, isFlash, isWS];
+  let tests = [isHtml, isCss, isJs, isXHR, isFont, isImage, isMedia, isWS];
   return tests.every(is => !is(item));
 }
 
 module.exports = {
   Filters: {
     all: all,
     html: isHtml,
     css: isCss,
     js: isJs,
     xhr: isXHR,
     fonts: isFont,
     images: isImage,
     media: isMedia,
-    flash: isFlash,
     ws: isWS,
     other: isOther,
   },
   isFreetextMatch,
 };

--- a/devtools/client/netmonitor/test/browser_net_filter-01.js
+++ b/devtools/client/netmonitor/test/browser_net_filter-01.js
@@ -211,23 +211,16 @@ add_task(function* () {
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-media-button"));
   testFilterButtons(monitor, "media");
   yield testContents([0, 0, 0, 0, 0, 1, 1, 0, 0]);
 
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-all-button"));
   EventUtils.sendMouseEvent({ type: "click" },
-    document.querySelector(".requests-list-filter-flash-button"));
-  testFilterButtons(monitor, "flash");
-  yield testContents([0, 0, 0, 0, 0, 0, 0, 1, 0]);
-
-  EventUtils.sendMouseEvent({ type: "click" },
-    document.querySelector(".requests-list-filter-all-button"));
-  EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-ws-button"));
   testFilterButtons(monitor, "ws");
   yield testContents([0, 0, 0, 0, 0, 0, 0, 0, 1]);
 
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-all-button"));
 
   testFilterButtons(monitor, "all");
@@ -260,52 +253,47 @@ add_task(function* () {
   // ...then combine multiple filters together.
 
   // Enable filtering for html and css; should show request of both type.
   setFreetextFilter("");
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-html-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-css-button"));
-  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]);
+  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 0, 0]);
   yield testContents([1, 1, 0, 0, 0, 0, 0, 0, 0]);
 
   // Html and css filter enabled and text filter should show just the html and css match.
   // Should not show both the items matching the button plus the items matching the text.
   setFreetextFilter("sample");
   yield testContents([1, 1, 0, 0, 0, 0, 0, 0, 0]);
-
-  EventUtils.sendMouseEvent({ type: "click" },
-    document.querySelector(".requests-list-filter-flash-button"));
   setFreetextFilter("");
-  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0]);
-  yield testContents([1, 1, 0, 0, 0, 0, 0, 1, 0]);
+  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 0, 0]);
+  yield testContents([1, 1, 0, 0, 0, 0, 0, 0, 0]);
 
   // Disable some filters. Only one left active.
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-css-button"));
-  EventUtils.sendMouseEvent({ type: "click" },
-    document.querySelector(".requests-list-filter-flash-button"));
   testFilterButtons(monitor, "html");
   yield testContents([1, 0, 0, 0, 0, 0, 0, 0, 0]);
 
   // Disable last active filter. Should toggle to all.
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-html-button"));
   testFilterButtons(monitor, "all");
   yield testContents([1, 1, 1, 1, 1, 1, 1, 1, 1]);
 
   // Enable few filters and click on all. Only "all" should be checked.
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-html-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-css-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-ws-button"));
-  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 0, 1]);
+  testFilterButtonsCustom(monitor, [0, 1, 1, 0, 0, 0, 0, 0, 1, 0]);
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-all-button"));
   testFilterButtons(monitor, "all");
   yield testContents([1, 1, 1, 1, 1, 1, 1, 1, 1]);
 
   yield teardown(monitor);
 
   function getSelectedIndex(state) {

--- a/devtools/client/netmonitor/test/browser_net_footer-summary.js
+++ b/devtools/client/netmonitor/test/browser_net_footer-summary.js
@@ -33,17 +33,17 @@ add_task(function* () {
     let wait = waitForNetworkEvents(monitor, 8);
     yield ContentTask.spawn(tab.linkedBrowser, {}, function* () {
       content.wrappedJSObject.performRequests('{ "getMedia": true, "getFlash": true }');
     });
     yield wait;
 
     testStatus();
 
-    let buttons = ["html", "css", "js", "xhr", "fonts", "images", "media", "flash"];
+    let buttons = ["html", "css", "js", "xhr", "fonts", "images", "media"];
     for (let button of buttons) {
       let buttonEl = document.querySelector(`.requests-list-filter-${button}-button`);
       EventUtils.sendMouseEvent({ type: "click" }, buttonEl);
       testStatus();
     }
   }
 
   yield teardown(monitor);

--- a/devtools/client/netmonitor/test/browser_net_statistics-02.js
+++ b/devtools/client/netmonitor/test/browser_net_statistics-02.js
@@ -21,17 +21,17 @@ add_task(function* () {
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-css-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-js-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-ws-button"));
   EventUtils.sendMouseEvent({ type: "click" },
     document.querySelector(".requests-list-filter-other-button"));
-  testFilterButtonsCustom(monitor, [0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1]);
+  testFilterButtonsCustom(monitor, [0, 1, 1, 1, 0, 0, 0, 0, 1, 1]);
   info("The correct filtering predicates are used before entering perf. analysis mode.");
 
   store.dispatch(Actions.openStatistics(connector, true));
 
   ok(document.querySelector(".statistics-panel"),
     "The main panel is switched to the statistics panel.");
 
   yield waitUntil(