--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -1482,16 +1482,23 @@ HTMLMediaElement::GetCurrentImage()
   if (!container) {
     return nullptr;
   }
 
   AutoLockImage lockImage(container);
   return lockImage.GetImage();
 }
 
+bool
+HTMLMediaElement::HasSuspendTaint() const
+{
+  MOZ_ASSERT(!mDecoder || (mDecoder->HasSuspendTaint() == mHasSuspendTaint));
+  return mHasSuspendTaint;
+}
+
 already_AddRefed<DOMMediaStream>
 HTMLMediaElement::GetSrcObject() const
 {
   NS_ASSERTION(!mSrcAttrStream || mSrcAttrStream->GetPlaybackStream(),
                "MediaStream should have been set up properly");
   RefPtr<DOMMediaStream> stream = mSrcAttrStream;
   return stream.forget();
 }

--- a/dom/html/HTMLMediaElement.h
+++ b/dom/html/HTMLMediaElement.h
@@ -600,18 +600,22 @@ public:
 
   already_AddRefed<MediaSource> GetMozMediaSourceObject() const;
   // Returns a string describing the state of the media player internal
   // data. Used for debugging purposes.
   void GetMozDebugReaderData(nsAString& aString);
 
   void MozDumpDebugInfo();
 
+  // For use by mochitests. Enabling pref "media.test.setVisible"
   void SetVisible(bool aVisible);
 
+  // For use by mochitests. Enabling pref "media.test.suspend-taint"
+  bool HasSuspendTaint() const;
+
   // Synchronously, return the next video frame and mark the element
   // unable to participate in decode suspending.
   //
   // This function is synchronous for cases where decoding has been suspended
   // and JS needs a frame to use in, eg., nsLayoutUtils::SurfaceFromElement()
   // via drawImage().
   layers::Image* GetCurrentImage();
 

--- a/dom/media/test/mochitest.ini
+++ b/dom/media/test/mochitest.ini
@@ -945,17 +945,19 @@ tags = webvtt
 
 # The tests below contain backend-specific tests. Write backend independent
 # tests rather than adding to this list.
 [test_can_play_type_webm.html]
 [test_can_play_type_wave.html]
 [test_fragment_noplay.html]
 [test_fragment_play.html]
 
+[test_background_video_no_suspend_disabled.html]
+tags = suspend
+[test_background_video_no_suspend_short_vid.html]
+tags = suspend
 [test_background_video_suspend.html]
 tags = suspend
 [test_background_video_suspend_ends.html]
 tags = suspend
-[test_background_video_no_suspend_short_vid.html]
-tags = suspend
-[test_background_video_no_suspend_disabled.html]
+[test_background_video_tainted_by_drawimage.html]
 tags = suspend
 [test_temporary_file_blob_video_plays.html]

--- a/dom/media/test/test_background_video_no_suspend_disabled.html
+++ b/dom/media/test/test_background_video_no_suspend_disabled.html
@@ -8,17 +8,17 @@
 <script>
 "use strict";
 
 var manager = new MediaTestManager;
 
 startTest({
   desc: "Test Background Video Doesn't Suspend When Feature Disabled.",
   prefs: [
-    [ 'media.test.setVisible', true ],
+    [ 'media.test.video-suspend', true ],
     [ 'media.suspend-bkgnd-video.enabled', false ],
     [ 'media.suspend-bkgnd-video.delay-ms', 0 ]
   ],
   tests: gDecodeSuspendTests,
   runTest: (test, token) => {
     let v = appendVideoToDoc(test.name, token);
     manager.started(token);
 
@@ -28,9 +28,9 @@ startTest({
       .then(() => {
         ok(true, 'Video ended before decode was suspended');
         manager.finished(token); })
       .catch((e) => {
         ok(false, 'Test Failed: ' + e.toString());
         manager.finished(token); });
   }
 });
-</script>
\ No newline at end of file
+</script>

--- a/dom/media/test/test_background_video_no_suspend_short_vid.html
+++ b/dom/media/test/test_background_video_no_suspend_short_vid.html
@@ -8,17 +8,17 @@
 <script>
 "use strict";
 
 var manager = new MediaTestManager;
 
 startTest({
   desc: "Test Background Video Doesn't Suspend When Timeout Is Longer Than Video.",
   prefs: [
-    [ 'media.test.setVisible', true ],
+    [ 'media.test.video-suspend', true ],
     [ 'media.suspend-bkgnd-video.enabled', true ],
     // Gizmo.mp4 is about 5.6s
     [ 'media.suspend-bkgnd-video.delay-ms', 10000 ]
   ],
   tests: gDecodeSuspendTests,
   runTest: (test, token) => {
     let v = appendVideoToDoc(test.name, token);
     manager.started(token);
@@ -30,9 +30,9 @@ startTest({
       .then(() => {
         ok(true, 'Video ended before decode was suspended');
         manager.finished(token); })
       .catch((e) => {
         ok(false, 'Test Failed: ' + e.toString());
         manager.finished(token); });
   }
 });
-</script>
\ No newline at end of file
+</script>

--- a/dom/media/test/test_background_video_suspend.html
+++ b/dom/media/test/test_background_video_suspend.html
@@ -14,17 +14,17 @@ function testDelay(v, start, min, max) {
   let end = performance.now();
   let delay = end - start;
   ok(delay > min && delay < max, `${v.token} suspended with a delay of ${delay} ms`);
 }
 
 startTest({
   desc: 'Test Background Video Suspends',
   prefs: [
-    [ "media.test.setVisible", true ],
+    [ "media.test.video-suspend", true ],
     [ "media.suspend-bkgnd-video.enabled", true ],
     // User a short delay to ensure video decode suspend happens before end
     // of video.
     [ "media.suspend-bkgnd-video.delay-ms", 100 ]
   ],
   tests: gDecodeSuspendTests,
   runTest: (test, token) => {
     let v = appendVideoToDoc(test.name, token);
@@ -40,9 +40,9 @@ startTest({
       })
       .then(() => waitUntilEnded(v))
       .then(() => {
         removeNodeAndSource(v);
         manager.finished(token);
       });
   }
 });
-</script>
\ No newline at end of file
+</script>

--- a/dom/media/test/test_background_video_suspend_ends.html
+++ b/dom/media/test/test_background_video_suspend_ends.html
@@ -8,17 +8,17 @@
 <script type="text/javascript">
 "use strict";
 
 var manager = new MediaTestManager;
 
 startTest({
   desc: "Test Background Suspended Video Fires 'ended' Event",
   prefs: [
-    [ "media.test.setVisible", true ],
+    [ "media.test.video-suspend", true ],
     [ "media.suspend-bkgnd-video.enabled", true ],
     // User a short delay to ensure video decode suspend happens before end
     // of video.
     [ "media.suspend-bkgnd-video.delay-ms", 1000 ]
   ],
   tests: gDecodeSuspendTests,
   runTest: (test, token) => {
     let v = appendVideoToDoc(test.name, token);

new file mode 100644
--- /dev/null
+++ b/dom/media/test/test_background_video_tainted_by_drawimage.html
@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Test Background Video Is Tainted By drawImage</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="manifest.js"></script>
+<script src="background_video.js"></script>
+<link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+var manager = new MediaTestManager;
+
+function drawVideoToCanvas(v) {
+  let w = v.width,
+      h = v.height,
+      c = document.createElement('canvas');
+  c.width = w;
+  c.height = h;
+  document.body.appendChild(c);
+
+  let gfx = c.getContext('2d');
+  if (!gfx) {
+    throw Error("Unable to obtain context '2d' from canvas");
+  }
+
+  gfx.drawImage(v, 0, 0, w, h);
+}
+
+startTest({
+  desc: 'Test Background Video Is Tainted By drawImage',
+  prefs: [
+    [ "media.test.video-suspend", true ],
+    [ "media.suspend-bkgnd-video.enabled", true ],
+    [ "media.suspend-bkgnd-video.delay-ms", 1000 ]
+  ],
+  tests: gDecodeSuspendTests,
+  runTest: (test, token) => {
+    let v = appendVideoToDoc(test.name, token);
+    manager.started(token);
+
+    waitUntilPlaying(v)
+      .then(() => {
+        drawVideoToCanvas(v);
+        ok(v.hasSuspendTaint(), "Video is tainted after drawing to canvas");
+        return checkVideoDoesntSuspend(v);
+      })
+      .then(() => {
+        ok(true, 'Video ended before decode was suspended');
+        manager.finished(token);
+      })
+      .catch((e) => {
+        ok(false, 'Test failed: ' + e.toString());
+        manager.finished(token);
+      });
+  }
+});
+</script>

--- a/dom/webidl/HTMLMediaElement.webidl
+++ b/dom/webidl/HTMLMediaElement.webidl
@@ -210,15 +210,22 @@ partial interface HTMLMediaElement {
  *     event and an "ended" event.
  */
 partial interface HTMLMediaElement {
   [Throws, Pref="media.seekToNextFrame.enabled"]
   Promise<void> seekToNextFrame();
 };
 
 /*
- * This is an API for simulating visibility changes to help debug and write
- * tests about suspend-video-decoding.
+ * This is an API to help debug and write tests about suspend-video-decoding.
+ *
+ * - SetVisible() is for simulating visibility changes.
+ * - HasSuspendTaint() is for querying that the element's decoder can
+     suspend video decoding because it has been tainted by an
+     operation, such as drawImage().
  */
 partial interface HTMLMediaElement {
-  [Pref="media.test.setVisible"]
+  [Pref="media.test.video-suspend"]
   void setVisible(boolean aVisible);
+
+  [Pref="media.test.video-suspend"]
+  boolean hasSuspendTaint();
 };