--- a/mobile/android/chrome/geckoview/ErrorPageEventHandler.js
+++ b/mobile/android/chrome/geckoview/ErrorPageEventHandler.js
@@ -1,14 +1,18 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* 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/. */
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://gre/modules/GeckoViewUtils.jsm");
+
+/* global debug:false, warn:false */
+GeckoViewUtils.initLogging("GeckoView.ErrorPageEventHandler", this);
 
 ChromeUtils.defineModuleGetter(this, "SSLExceptions",
                                "resource://gre/modules/SSLExceptions.jsm");
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   Services: "resource://gre/modules/Services.jsm",
 });
 

--- a/mobile/android/chrome/geckoview/GeckoViewContent.js
+++ b/mobile/android/chrome/geckoview/GeckoViewContent.js
@@ -192,9 +192,10 @@ class GeckoViewContent extends GeckoView
         this.eventDispatcher.sendRequest({
           type: "GeckoView:DOMWindowClose"
         });
         break;
     }
   }
 }
 
-var contentListener = new GeckoViewContent("GeckoViewContent", this);
+let {debug, warn} = GeckoViewContent.initLogging("GeckoViewContent");
+let module = GeckoViewContent.create(this);

--- a/mobile/android/chrome/geckoview/GeckoViewContentSettings.js
+++ b/mobile/android/chrome/geckoview/GeckoViewContentSettings.js
@@ -66,9 +66,10 @@ class GeckoViewContentSettings extends G
   set displayMode(aMode) {
     const docShell = content && GeckoViewUtils.getRootDocShell(content);
     if (docShell) {
       docShell.displayMode = aMode;
     }
   }
 }
 
-var settings = new GeckoViewContentSettings("GeckoViewSettings", this);
+let {debug, warn} = GeckoViewContentSettings.initLogging("GeckoViewSettings");
+let module = GeckoViewContentSettings.create(this);

--- a/mobile/android/chrome/geckoview/GeckoViewNavigationContent.js
+++ b/mobile/android/chrome/geckoview/GeckoViewNavigationContent.js
@@ -42,9 +42,10 @@ class GeckoViewNavigationContent extends
       addEventListener("click", ErrorPageEventHandler, true);
     }
 
     return LoadURIDelegate.load(this.eventDispatcher, aUri, aWhere, aFlags,
                                 aTriggeringPrincipal);
   }
 }
 
-var navigationListener = new GeckoViewNavigationContent("GeckoViewNavigation", this);
+let {debug, warn} = GeckoViewNavigationContent.initLogging("GeckoViewNavigation");
+let module = GeckoViewNavigationContent.create(this);

--- a/mobile/android/chrome/geckoview/GeckoViewScrollContent.js
+++ b/mobile/android/chrome/geckoview/GeckoViewScrollContent.js
@@ -38,9 +38,11 @@ class GeckoViewScrollContent extends Gec
           type: "GeckoView:ScrollChanged",
           scrollX: Math.round(content.scrollX),
           scrollY: Math.round(content.scrollY)
         });
         break;
     }
   }
 }
-var scrollListener = new GeckoViewScrollContent("GeckoViewScroll", this);
+
+let {debug, warn} = GeckoViewScrollContent.initLogging("GeckoViewScroll");
+let module = GeckoViewScrollContent.create(this);

--- a/mobile/android/chrome/geckoview/GeckoViewSelectionActionContent.js
+++ b/mobile/android/chrome/geckoview/GeckoViewSelectionActionContent.js
@@ -253,10 +253,11 @@ class GeckoViewSelectionActionContent ex
       });
 
     } else {
       dump("Unknown reason: " + reason);
     }
   }
 }
 
-var selectionActionListener =
-    new GeckoViewSelectionActionContent("GeckoViewSelectionAction", this);
+let {debug, warn} =
+    GeckoViewSelectionActionContent.initLogging("GeckoViewSelectionAction");
+let module = GeckoViewSelectionActionContent.create(this);

--- a/mobile/android/chrome/geckoview/geckoview.js
+++ b/mobile/android/chrome/geckoview/geckoview.js
@@ -1,21 +1,22 @@
 /* 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/. */
 
 "use strict";
 
-ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
-ChromeUtils.defineModuleGetter(this, "EventDispatcher",
-  "resource://gre/modules/Messaging.jsm");
-ChromeUtils.defineModuleGetter(this, "Services",
-  "resource://gre/modules/Services.jsm");
+XPCOMUtils.defineLazyModuleGetters(this, {
+  EventDispatcher: "resource://gre/modules/Messaging.jsm",
+  GeckoViewUtils: "resource://gre/modules/GeckoViewUtils.jsm",
+  Services: "resource://gre/modules/Services.jsm",
+});
+
 XPCOMUtils.defineLazyGetter(this, "WindowEventDispatcher",
   () => EventDispatcher.for(window));
 
 XPCOMUtils.defineLazyGetter(this, "dump", () =>
     ChromeUtils.import("resource://gre/modules/AndroidLog.jsm",
                        {}).AndroidLog.d.bind(null, "View"));
 
 // Creates and manages GeckoView modules.
@@ -27,18 +28,21 @@ XPCOMUtils.defineLazyGetter(this, "dump"
 var ModuleManager = {
   init: function(aBrowser) {
     this.browser = aBrowser;
     this.modules = new Map();
   },
 
   add: function(aResource, aType, ...aArgs) {
     this.remove(aType);
-    let scope = {};
-    ChromeUtils.import(aResource, scope);
+
+    const scope = {};
+    const global = ChromeUtils.import(aResource, scope);
+    const tag = aType.replace("GeckoView", "GeckoView.");
+    GeckoViewUtils.initLogging(tag, global);
 
     this.modules.set(aType, new scope[aType](
       aType, window, this.browser, WindowEventDispatcher, ...aArgs
     ));
   },
 
   remove: function(aType) {
     this.modules.delete(aType);
@@ -53,16 +57,18 @@ function createBrowser() {
   const browser = window.browser = document.createElement("browser");
   browser.setAttribute("type", "content");
   browser.setAttribute("primary", "true");
   browser.setAttribute("flex", "1");
   return browser;
 }
 
 function startup() {
+  GeckoViewUtils.initLogging("GeckoView.XUL", window);
+
   const browser = createBrowser();
   ModuleManager.init(browser);
 
   ModuleManager.add("resource://gre/modules/GeckoViewNavigation.jsm",
                     "GeckoViewNavigation");
   ModuleManager.add("resource://gre/modules/GeckoViewSettings.jsm",
                     "GeckoViewSettings");
   ModuleManager.add("resource://gre/modules/GeckoViewContent.jsm",

--- a/mobile/android/components/geckoview/GeckoViewExternalAppService.js
+++ b/mobile/android/components/geckoview/GeckoViewExternalAppService.js
@@ -1,15 +1,19 @@
 /* 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/. */
 
 "use strict";
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://gre/modules/GeckoViewUtils.jsm");
+
+/* global debug:false, warn:false */
+GeckoViewUtils.initLogging("GeckoView.ExternalAppService", this);
 
 ChromeUtils.defineModuleGetter(this, "EventDispatcher",
   "resource://gre/modules/Messaging.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "dump", () =>
     ChromeUtils.import("resource://gre/modules/AndroidLog.jsm",
                        {}).AndroidLog.d.bind(null, "ViewContent"));
 

new file mode 100644
--- /dev/null
+++ b/mobile/android/modules/geckoview/.eslintrc.js
@@ -0,0 +1,8 @@
+"use strict";
+
+module.exports = {
+  "globals": {
+    "debug": false,
+    "warn": false,
+  },
+};

--- a/mobile/android/modules/geckoview/GeckoViewContentModule.jsm
+++ b/mobile/android/modules/geckoview/GeckoViewContentModule.jsm
@@ -2,29 +2,42 @@
  * 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/. */
 
 "use strict";
 
 var EXPORTED_SYMBOLS = ["GeckoViewContentModule"];
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://gre/modules/GeckoViewUtils.jsm");
+
+GeckoViewUtils.initLogging("GeckoView.Module.[C]", this);
 
 ChromeUtils.defineModuleGetter(this, "EventDispatcher",
   "resource://gre/modules/Messaging.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "dump", () =>
     ChromeUtils.import("resource://gre/modules/AndroidLog.jsm",
                        {}).AndroidLog.d.bind(null, "ViewContentModule"));
 
 // function debug(aMsg) {
 //   dump(aMsg);
 // }
 
 class GeckoViewContentModule {
+  static initLogging(aModuleName) {
+    this._moduleName = aModuleName;
+    const tag = aModuleName.replace("GeckoView", "GeckoView.") + ".[C]";
+    return GeckoViewUtils.initLogging(tag, {});
+  }
+
+  static create(aGlobal, aModuleName) {
+    return new this(aModuleName || this._moduleName, aGlobal);
+  }
+
   constructor(aModuleName, aMessageManager) {
     this.moduleName = aModuleName;
     this.messageManager = aMessageManager;
     this.eventDispatcher = EventDispatcher.forMessageManager(aMessageManager);
 
     this.messageManager.addMessageListener(
       "GeckoView:UpdateSettings",
       aMsg => {

--- a/mobile/android/modules/geckoview/GeckoViewModule.jsm
+++ b/mobile/android/modules/geckoview/GeckoViewModule.jsm
@@ -2,16 +2,19 @@
  * 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/. */
 
 "use strict";
 
 var EXPORTED_SYMBOLS = ["GeckoViewModule"];
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://gre/modules/GeckoViewUtils.jsm");
+
+GeckoViewUtils.initLogging("GeckoView.Module", this);
 
 XPCOMUtils.defineLazyGetter(this, "dump", () =>
     ChromeUtils.import("resource://gre/modules/AndroidLog.jsm",
                        {}).AndroidLog.d.bind(null, "ViewModule"));
 
 // function debug(aMsg) {
 //   dump(aMsg);
 // }

--- a/mobile/android/modules/geckoview/GeckoViewUtils.jsm
+++ b/mobile/android/modules/geckoview/GeckoViewUtils.jsm
@@ -1,18 +1,19 @@
 /* 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/. */
 "use strict";
 
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetters(this, {
+  EventDispatcher: "resource://gre/modules/Messaging.jsm",
+  Log: "resource://gre/modules/Log.jsm",
   Services: "resource://gre/modules/Services.jsm",
-  EventDispatcher: "resource://gre/modules/Messaging.jsm",
 });
 
 var EXPORTED_SYMBOLS = ["GeckoViewUtils"];
 
 var GeckoViewUtils = {
   /**
    * Define a lazy getter that loads an object from external code, and
    * optionally handles observer and/or message manager notifications for the
@@ -247,12 +248,96 @@ var GeckoViewUtils = {
       dispatcher = this.getDispatcherForWindow(
           iter.getNext().QueryInterface(Ci.nsIDOMWindow));
       if (dispatcher) {
         return dispatcher;
       }
     }
     return null;
   },
+
+  /**
+   * Add logging functions to the specified scope that forward to the given
+   * Log.jsm logger. Currently "debug" and "warn" functions are supported. To
+   * log something, call the function through a template literal:
+   *
+   *   function foo(bar, baz) {
+   *     debug `hello world`;
+   *     debug `foo called with ${bar} as bar`;
+   *     warn `this is a warning for ${baz}`;
+   *   }
+   *
+   * An inline format can also be used for logging:
+   *
+   *   let bar = 42;
+   *   do_something(bar); // No log.
+   *   do_something(debug.foo = bar); // Output "foo = 42" to the log.
+   *
+   * @param tag Name of the Log.jsm logger to forward logs to.
+   * @param scope Scope to add the logging functions to.
+   */
+  initLogging: function(tag, scope) {
+    // Only provide two levels for simplicity.
+    // For "info", use "debug" instead.
+    // For "error", throw an actual JS error instead.
+    for (const level of ["debug", "warn"]) {
+      const log = (strings, ...exprs) =>
+          this._log(log.logger, level, strings, exprs);
+
+      XPCOMUtils.defineLazyGetter(log, "logger", _ => {
+        const logger = Log.repository.getLogger(tag);
+        logger.parent = this.rootLogger;
+        return logger;
+      });
+
+      scope[level] = new Proxy(log, {
+        set: (obj, prop, value) => obj([prop + " = ", ""], value) || true,
+      });
+    }
+    return scope;
+  },
+
+  get rootLogger() {
+    if (!this._rootLogger) {
+      this._rootLogger = Log.repository.getLogger("GeckoView");
+      this._rootLogger.addAppender(new Log.AndroidAppender());
+    }
+    return this._rootLogger;
+  },
+
+  _log: function(logger, level, strings, exprs) {
+    if (!Array.isArray(strings)) {
+      const [, file, line] =
+          (new Error()).stack.match(/.*\n.*\n.*@(.*):(\d+):/);
+      throw Error(`Expecting template literal: ${level} \`foo \${bar}\``,
+                  file, +line);
+    }
+
+    // Do some GeckoView-specific formatting:
+    // 1) Heuristically format flags as hex.
+    // 2) Heuristically format nsresult as string name or hex.
+    for (let i = 0; i < exprs.length; i++) {
+      const expr = exprs[i];
+      switch (typeof expr) {
+        case "number":
+          if (expr > 0 && /\ba?[fF]lags?[\s=:]+$/.test(strings[i])) {
+            // Likely a flag; display in hex.
+            exprs[i] = `0x${expr.toString(0x10)}`;
+          } else if (expr >= 0 && /\b(a?[sS]tatus|rv)[\s=:]+$/.test(strings[i])) {
+            // Likely an nsresult; display in name or hex.
+            exprs[i] = `0x${expr.toString(0x10)}`;
+            for (const name in Cr) {
+              if (expr === Cr[name]) {
+                exprs[i] = name;
+                break;
+              }
+            }
+          }
+          break;
+      }
+    }
+
+    return logger[level](strings, ...exprs);
+  },
 };
 
 XPCOMUtils.defineLazyGetter(GeckoViewUtils, "IS_PARENT_PROCESS", _ =>
     Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_DEFAULT);