diff --git a/dom/canvas/test/mochitest.ini b/dom/canvas/test/mochitest.ini
index 2fddb72ef7a3..71cbcf769de5 100644
--- a/dom/canvas/test/mochitest.ini
+++ b/dom/canvas/test/mochitest.ini
@@ -193,6 +193,7 @@ tags = imagebitmap
 [test_ImageData_ctor.html]
 [test_isPointInStroke.html]
 [test_mozGetAsFile.html]
+prefs = canvas.mozgetasfile.enabled=true
 [test_strokeText_throw.html]
 [test_toBlob.html]
 [test_toBlob_zero_dimension.html]
diff --git a/dom/canvas/test/test_toBlob.html b/dom/canvas/test/test_toBlob.html
index 34d87dba8a90..bcffdc0f16a6 100644
--- a/dom/canvas/test/test_toBlob.html
+++ b/dom/canvas/test/test_toBlob.html
@@ -14,7 +14,7 @@ function BlobListener(type, canvas, callback, file)
   reader.onload =
     function(e) {
       is(e.target.result, canvas.toDataURL(type),
-  "<canvas>.mozGetAsFile().getAsDataURL() should equal <canvas>.toDataURL()");
+  "<canvas>.toBlob() should equal <canvas>.toDataURL()");
       callback(canvas);
     };
   reader.readAsDataURL(file);
diff --git a/dom/file/tests/common_blob.js b/dom/file/tests/common_blob.js
index dd1963a9ebd4..1750c71a1067 100644
--- a/dom/file/tests/common_blob.js
+++ b/dom/file/tests/common_blob.js
@@ -135,7 +135,11 @@ function testBlob(file, contents, testName) {
 function testSlice(file, size, type, contents, fileType, range) {
   is(file.type, type, fileType + " file is correct type");
   is(file.size, size, fileType + " file is correct size");
-  ok(file instanceof File, fileType + " file is a File");
+  if (fileType == "fileFile") {
+    ok(file instanceof File, fileType + " file is a File");
+  } else if (fileType == "memFile") {
+    ok(!(file instanceof File), fileType + " file is not a File");
+  }
   ok(file instanceof Blob, fileType + " file is also a Blob");
 
   let slice = file.slice(0, size);
@@ -377,3 +381,15 @@ function createFile(data, name) {
     });
   });
 }
+
+function toBlobPromise(canvas) {
+  function BlobListener(callback, file) {
+    var reader = new FileReader();
+    reader.onload = () => callback(file);
+    reader.readAsDataURL(file);
+  }
+
+  return new Promise(resolve => {
+    canvas.toBlob(BlobListener.bind(undefined, resolve));
+  });
+}
diff --git a/dom/file/tests/test_fileapi_slice_memFile_1.html b/dom/file/tests/test_fileapi_slice_memFile_1.html
index 53532d52df18..56d63d15ba58 100644
--- a/dom/file/tests/test_fileapi_slice_memFile_1.html
+++ b/dom/file/tests/test_fileapi_slice_memFile_1.html
@@ -21,7 +21,12 @@ SimpleTest.requestLongerTimeout(4);
 createCanvasURL()
 .then(data => {
   let cx = $("canvas").getContext('2d');
-  let memFile = cx.canvas.mozGetAsFile("image/png");
+  return Promise.all([toBlobPromise(cx.canvas),
+                      Promise.resolve(data)]);
+})
+
+.then(args => {
+  let [memFile, data] = args;
   return testSlice(memFile, data.length, "image/png", data, "memFile", RANGE_1);
 })
 
diff --git a/dom/file/tests/test_fileapi_slice_memFile_2.html b/dom/file/tests/test_fileapi_slice_memFile_2.html
index 3f9793a1fcea..aef8813bf5f3 100644
--- a/dom/file/tests/test_fileapi_slice_memFile_2.html
+++ b/dom/file/tests/test_fileapi_slice_memFile_2.html
@@ -21,7 +21,12 @@ SimpleTest.requestLongerTimeout(4);
 createCanvasURL()
 .then(data => {
   let cx = $("canvas").getContext('2d');
-  let memFile = cx.canvas.mozGetAsFile("image/png");
+  return Promise.all([toBlobPromise(cx.canvas),
+                      Promise.resolve(data)]);
+})
+
+.then(args => {
+  let [memFile, data] = args;
   return testSlice(memFile, data.length, "image/png", data, "memFile", RANGE_2);
 })
 
diff --git a/dom/webidl/HTMLCanvasElement.webidl b/dom/webidl/HTMLCanvasElement.webidl
index 1ecd479afcdf..dbb23168b8a2 100644
--- a/dom/webidl/HTMLCanvasElement.webidl
+++ b/dom/webidl/HTMLCanvasElement.webidl
@@ -38,7 +38,7 @@ interface HTMLCanvasElement : HTMLElement {
 partial interface HTMLCanvasElement {
   [Pure, SetterThrows]
            attribute boolean mozOpaque;
-  [Throws, NeedsSubjectPrincipal]
+  [Throws, NeedsSubjectPrincipal, Pref="canvas.mozgetasfile.enabled"]
   File mozGetAsFile(DOMString name, optional DOMString? type = null);
   // A Mozilla-only extension to get a canvas context backed by double-buffered
   // shared memory. Only privileged callers can call this.
diff --git a/image/test/crashtests/crashtests.list b/image/test/crashtests/crashtests.list
index 2a0b55aa9e37..cb693fca63c1 100644
--- a/image/test/crashtests/crashtests.list
+++ b/image/test/crashtests/crashtests.list
@@ -9,7 +9,7 @@ load 570451.png
 # Bug 1390704 - Skip on debug because it triggers a quadratic behavior that makes it take
 # so much time that it can trip on the reftest timeout of 5 minutes.
 skip-if(Android||isDebugBuild) load 694165-1.xhtml
-load 681190.html
+pref(canvas.mozgetasfile.enabled,true) load 681190.html
 load 732319-1.html
 load 844403-1.html
 load 856616.gif
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index 36a690efa03c..c437c9a013cd 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -1063,6 +1063,12 @@
   value: false
   mirror: always
 
+# Provide ability to turn on support for canvas mozGetAsFile API.
+- name: canvas.mozgetasfile.enabled
+  type: bool
+  value: false
+  mirror: always
+
 #---------------------------------------------------------------------------
 # Prefs starting with "channelclassifier."
 #---------------------------------------------------------------------------