Add performance warnings to Deprecated module.

Adds a dedicated handler for performance warnings to be logged to
consoles if known performance-impacting methods are called.
Search service init is changed from a deprecation warning to a
performance warning for synchronous init.
This also re-enables the warning for the Basilisk & Co. search service
initialization which was previously removed in [a930a79]

See also the discussion on #916.

modules/libpref/init/all.js

@@ -956,6 +956,9 @@ pref("toolkit.asyncshutdown.log", false);
 // Enable deprecation warnings.
 pref("devtools.errorconsole.deprecation_warnings", true);
 
+// Enable performance warnings.
+pref("devtools.errorconsole.performance_warnings", true);
+
 // Disable debugging chrome
 pref("devtools.chrome.enabled", false);
 

toolkit/components/search/current/nsSearchService.js

@@ -21,6 +21,8 @@ XPCOMUtils.defineLazyModuleGetter(this, "OS",
   "resource://gre/modules/osfile.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Task",
   "resource://gre/modules/Task.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Deprecated",
+  "resource://gre/modules/Deprecated.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "SearchStaticData",
   "resource://gre/modules/SearchStaticData.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "setTimeout",
@@ -2691,6 +2693,13 @@ SearchService.prototype = {
       return;
     }
 
+    let performanceWarning =
+      "Search service falling back to synchronous initialization. " +
+      "This is generally the consequence of an add-on using a deprecated " +
+      "search service API.";
+    Deprecated.perfWarning(performanceWarning, "https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/nsIBrowserSearchService#async_warning");
+    LOG(performanceWarning);
+
     this._syncInit();
     if (!Components.isSuccessCode(this._initRV)) {
       throw this._initRV;

toolkit/components/search/orginal/nsSearchService.js

@@ -2917,12 +2917,12 @@ SearchService.prototype = {
       return;
     }
 
-    let warning =
+    let performanceWarning =
       "Search service falling back to synchronous initialization. " +
       "This is generally the consequence of an add-on using a deprecated " +
       "search service API.";
-    Deprecated.warning(warning, "https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/nsIBrowserSearchService#async_warning");
+    Deprecated.perfWarning(performanceWarning, "https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/nsIBrowserSearchService#async_warning");
-    LOG(warning);
+    LOG(performanceWarning);
 
     engineMetadataService.syncInit();
     this._syncInit();

toolkit/modules/Deprecated.jsm

@@ -9,15 +9,21 @@ this.EXPORTED_SYMBOLS = [ "Deprecated" ];
 const Cu = Components.utils;
 const Ci = Components.interfaces;
 const PREF_DEPRECATION_WARNINGS = "devtools.errorconsole.deprecation_warnings";
+const PREF_PERFORMANCE_WARNINGS = "devtools.errorconsole.performance_warnings";
 
 Cu.import("resource://gre/modules/Services.jsm");
 
 // A flag that indicates whether deprecation warnings should be logged.
-var logWarnings = Services.prefs.getBoolPref(PREF_DEPRECATION_WARNINGS);
+var logDepWarnings = Services.prefs.getBoolPref(PREF_DEPRECATION_WARNINGS);
+var logPerfWarnings = Services.prefs.getBoolPref(PREF_PERFORMANCE_WARNINGS);
 
 Services.prefs.addObserver(PREF_DEPRECATION_WARNINGS,
   function (aSubject, aTopic, aData) {
-    logWarnings = Services.prefs.getBoolPref(PREF_DEPRECATION_WARNINGS);
+    logDepWarnings = Services.prefs.getBoolPref(PREF_DEPRECATION_WARNINGS);
+  }, false);
+Services.prefs.addObserver(PREF_PERFORMANCE_WARNINGS,
+  function (aSubject, aTopic, aData) {
+    logPerfWarnings = Services.prefs.getBoolPref(PREF_PERFORMANCE_WARNINGS);
   }, false);
 
 /**
@@ -58,7 +64,7 @@ this.Deprecated = {
    *        logged.
    */
   warning: function (aText, aUrl, aStack) {
-    if (!logWarnings) {
+    if (!logDepWarnings) {
       return;
     }
 
@@ -71,7 +77,42 @@ this.Deprecated = {
 
     let textMessage = "DEPRECATION WARNING: " + aText +
       "\nYou may find more details about this deprecation at: " +
-      aUrl + "\n" +
+      aUrl + "\nCallstack:\n" +
+      // Append a callstack part to the deprecation message.
+      stringifyCallstack(aStack);
+
+    // Report deprecation warning.
+    Cu.reportError(textMessage);
+  },
+
+  /**
+   * Log a performance warning.
+   *
+   * @param string aText
+   *        Performance issue warning text.
+   * @param string aUrl
+   *        A URL pointing to documentation describing performance
+   *        issue and the way to address it.
+   * @param nsIStackFrame aStack
+   *        An optional callstack. If it is not provided a
+   *        snapshot of the current JavaScript callstack will be
+   *        logged.
+   */
+  perfWarning: function (aText, aUrl, aStack) {
+    if (!logPerfWarnings) {
+      return;
+    }
+
+    // If URL is not provided, report an error.
+    if (!aUrl) {
+      Cu.reportError("Error in Deprecated.perfWarning: warnings must " +
+        "provide a URL documenting this performance issue.");
+      return;
+    }
+
+    let textMessage = "PERFORMANCE WARNING: " + aText +
+      "\nYou may find more details about this problem at: " +
+      aUrl + "\nCallstack:\n" +
       // Append a callstack part to the deprecation message.
       stringifyCallstack(aStack);