Bug 1449523 - ContentLinkHandler only picks perfectly sized icons. r=Mardak

MozReview-Commit-ID: IY5vOIliWWC

--HG--
extra : rebase_source : 125201afee6771d22ed5079e70b966bb0d193f07

browser/base/content/test/favicons/browser_preferred_icons.js

@@ -164,3 +164,28 @@ add_task(async function guess_invalid() {
   // Must have at least one test.
   Assert.ok(true, "The expected icon has been set");
 });
+
+add_task(async function guess_bestSized() {
+  let preferredWidth = 16 * Math.ceil(window.devicePixelRatio);
+  let promise = waitIcon(ROOT + "icon3.png");
+  await createLinks([
+    { href: ROOT + "icon.png",
+      type: "image/png",
+      size: preferredWidth - 1
+    },
+    { href: ROOT + "icon2.png",
+      type: "image/png",
+    },
+    { href: ROOT + "icon3.png",
+      type: "image/png",
+      size: preferredWidth + 1
+    },
+    { href: ROOT + "icon4.png",
+      type: "image/png",
+      size: preferredWidth + 2
+    },
+  ]);
+  await promise;
+  // Must have at least one test.
+  Assert.ok(true, "The expected icon has been set");
+});

browser/modules/ContentLinkHandler.jsm

@@ -160,6 +160,7 @@ function faviconTimeoutCallback(aFaviconLoads, aPageUrl, aChromeGlobal) {
 
   let preferredIcon;
   let preferredWidth = 16 * Math.ceil(aChromeGlobal.content.devicePixelRatio);
+  let bestSizedIcon;
   // Other links with the "icon" tag are the default icons
   let defaultIcon;
   // Rich icons are either apple-touch or fluid icons, or the ones of the
@@ -178,6 +179,13 @@ function faviconTimeoutCallback(aFaviconLoads, aPageUrl, aChromeGlobal) {
       } else if (guessType(icon) == TYPE_ICO && (!preferredIcon || guessType(preferredIcon) == TYPE_ICO)) {
         preferredIcon = icon;
       }
+
+      // Check for an icon larger yet closest to preferredWidth, that can be
+      // downscaled efficiently.
+      if (icon.width >= preferredWidth &&
+          (!bestSizedIcon || bestSizedIcon.width >= icon.width)) {
+        bestSizedIcon = icon;
+      }
     }
 
     // Note that some sites use hi-res icons without specifying them as
@@ -193,7 +201,8 @@ function faviconTimeoutCallback(aFaviconLoads, aPageUrl, aChromeGlobal) {
 
   // Now set the favicons for the page in the following order:
   // 1. Set the best rich icon if any.
-  // 2. Set the preferred one if any, otherwise use the default one.
+  // 2. Set the preferred one if any, otherwise check if there's a better
+  //    sized fit.
   // This order allows smaller icon frames to eventually override rich icon
   // frames.
   if (largestRichIcon) {
@@ -201,6 +210,8 @@ function faviconTimeoutCallback(aFaviconLoads, aPageUrl, aChromeGlobal) {
   }
   if (preferredIcon) {
     setIconForLink(preferredIcon, aChromeGlobal);
+  } else if (bestSizedIcon) {
+    setIconForLink(bestSizedIcon, aChromeGlobal);
   } else if (defaultIcon) {
     setIconForLink(defaultIcon, aChromeGlobal);
   }