--- a/dom/base/DOMPrefsInternal.h
+++ b/dom/base/DOMPrefsInternal.h
@@ -33,16 +33,17 @@ DOM_PREF(PromiseRejectionEventsEnabled, 
 DOM_PREF(PushEnabled, "dom.push.enabled")
 DOM_PREF(StreamsEnabled, "dom.streams.enabled")
 DOM_PREF(RequestContextEnabled, "dom.requestcontext.enabled")
 DOM_PREF(OffscreenCanvasEnabled, "gfx.offscreencanvas.enabled")
 DOM_PREF(WebkitBlinkDirectoryPickerEnabled, "dom.webkitBlink.dirPicker.enabled")
 DOM_PREF(NetworkInformationEnabled, "dom.netinfo.enabled")
 DOM_PREF(FetchObserverEnabled, "dom.fetchObserver.enabled")
 DOM_PREF(ResistFingerprintingEnabled, "privacy.resistFingerprinting")
+DOM_PREF(EnableAutoDeclineCanvasPrompts, "privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts")
 DOM_PREF(DevToolsEnabled, "devtools.enabled")
 DOM_PREF(PerformanceObserverEnabled, "dom.enable_performance_observer")
 
 DOM_WEBIDL_PREF(ImageBitmapExtensionsEnabled)
 DOM_WEBIDL_PREF(DOMCachesEnabled)
 DOM_WEBIDL_PREF(NotificationEnabledInServiceWorkers)
 DOM_WEBIDL_PREF(NotificationRIEnabled)
 DOM_WEBIDL_PREF(ServiceWorkersEnabled)

--- a/dom/canvas/CanvasUtils.cpp
+++ b/dom/canvas/CanvasUtils.cpp
@@ -9,16 +9,17 @@
 #include "nsIServiceManager.h"
 
 #include "nsIConsoleService.h"
 #include "nsIDOMCanvasRenderingContext2D.h"
 #include "nsICanvasRenderingContextInternal.h"
 #include "nsIHTMLCollection.h"
 #include "mozilla/dom/HTMLCanvasElement.h"
 #include "mozilla/dom/TabChild.h"
+#include "mozilla/EventStateManager.h"
 #include "nsIPrincipal.h"
 
 #include "nsGfxCIID.h"
 
 #include "nsTArray.h"
 
 #include "CanvasUtils.h"
 #include "mozilla/gfx/Matrix.h"
@@ -137,18 +138,33 @@ bool IsImageExtractionAllowed(nsIDocumen
         return true;
     case nsIPermissionManager::DENY_ACTION:
         return false;
     default:
         break;
     }
 
     // At this point, permission is unknown (nsIPermissionManager::UNKNOWN_ACTION).
+
+    // Check if the request is in response to user input
+    if (DOMPrefs::EnableAutoDeclineCanvasPrompts() && !EventStateManager::IsHandlingUserInput()) {
+        nsAutoCString message;
+        message.AppendPrintf("Blocked %s in page %s from extracting canvas data because no user input was detected.",
+                             docURISpec.get(), topLevelDocURISpec.get());
+        if (isScriptKnown) {
+            message.AppendPrintf(" %s:%u.", scriptFile.get(), scriptLine);
+        }
+        nsContentUtils::LogMessageToConsole(message.get());
+
+        return false;
+    }
+
+    // It was in response to user input, so log and display the prompt.
     nsAutoCString message;
-    message.AppendPrintf("Blocked %s in page %s from extracting canvas data.",
+    message.AppendPrintf("Blocked %s in page %s from extracting canvas data, but prompting the user.",
                          docURISpec.get(), topLevelDocURISpec.get());
     if (isScriptKnown) {
         message.AppendPrintf(" %s:%u.", scriptFile.get(), scriptLine);
     }
     nsContentUtils::LogMessageToConsole(message.get());
 
     // Prompt the user (asynchronous).
     if (XRE_IsContentProcess()) {

--- a/dom/ipc/ContentPrefs.cpp
+++ b/dom/ipc/ContentPrefs.cpp
@@ -283,16 +283,17 @@ const char* mozilla::dom::ContentPrefs::
   "network.tcp.keepalive.retry_interval",
   "network.tcp.sendbuffer",
   "nglayout.debug.invalidation",
   "privacy.donottrackheader.enabled",
   "privacy.firstparty.isolate",
   "privacy.firstparty.isolate.restrict_opener_access",
   "privacy.reduceTimerPrecision",
   "privacy.resistFingerprinting",
+  "privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts",
   "privacy.resistFingerprinting.reduceTimerPrecision.microseconds",
   "privacy.resistFingerprinting.target_video_res",
   "privacy.resistFingerprinting.video_dropped_ratio",
   "privacy.resistFingerprinting.video_frames_per_sec",
   "privacy.trackingprotection.lower_network_priority",
   "privacy.window.maxInnerHeight",
   "privacy.window.maxInnerWidth",
   "security.csp.enable",

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1395,16 +1395,22 @@ pref("privacy.trackingprotection.annotat
 // First Party Isolation (double keying), disabled by default
 pref("privacy.firstparty.isolate",                        false);
 // If false, two windows in the same domain with different first party domains
 // (top level URLs) can access resources through window.opener.
 // This pref is effective only when "privacy.firstparty.isolate" is true.
 pref("privacy.firstparty.isolate.restrict_opener_access", true);
 // Anti-fingerprinting, disabled by default
 pref("privacy.resistFingerprinting", false);
+// We automatically decline canvas permission requests if they are not initiated
+// from user input. Just in case that breaks something, we allow the user to revert
+// this behaior with this obscure pref. We do not intend to support this long term.
+// If you do set it, to work around some broken website, please file a bug with
+// information so we can understand why it is needed.
+pref("privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts", true);
 // A subset of Resist Fingerprinting protections focused specifically on timers for testing
 // This affects the Animation API, the performance APIs, Date.getTime, Event.timestamp,
 //   File.lastModified, audioContext.currentTime, canvas.captureStream.currentTime
 pref("privacy.reduceTimerPrecision", true);
 // Dynamically tune the resolution of the timer reduction for both of the two above prefs
 pref("privacy.resistFingerprinting.reduceTimerPrecision.microseconds", 2000);
 // Lower the priority of network loads for resources on the tracking protection list.
 // Note that this requires the privacy.trackingprotection.annotate_channels pref to be on in order to have any effect.