Settings: Implement heuristic for finding site group favicon.

Currently the favicon shown for etld+1 is simply using the favicon of
the first origin. This CL implement heuristic for finding a good
favicon.
The rules are:
1. Find the origin with format "www.etld+1".
2. If there is no origin with format "www.etld+1", find the origin with
largest storage, and use the number of cookies as tie breaker.

BUG=930626,835712

Change-Id: I374e079568020a7a6df6ec80e65736c29eead9ba
Reviewed-on: https://chromium-review.googlesource.com/c/1475561Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Patti <patricialor@chromium.org>
Commit-Queue: Maggie Cai <mxcai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634397}

chrome/browser/resources/settings/site_settings/site_entry.js

@@ -199,14 +199,34 @@ Polymer({
   /**
    * Get an appropriate favicon that represents this group of eTLD+1 sites as a
    * whole.
-   * @param {SiteGroup} siteGroup The eTLD+1 group of origins.
+   * @param {!SiteGroup} siteGroup The eTLD+1 group of origins.
    * @return {string} URL that is used for fetching the favicon
    * @private
    */
   getSiteGroupIcon_: function(siteGroup) {
-    // TODO(https://crbug.com/835712): Implement heuristic for finding a good
-    // favicon.
-    return siteGroup.origins[0].origin;
+    const origins = siteGroup.origins;
+    assert(origins);
+    assert(origins.length >= 1);
+    if (origins.length == 1) {
+      return origins[0].origin;
+    }
+    // If we can find a origin with format "www.etld+1", use the favicon of this
+    // origin. Otherwise find the origin with largest storage, and use the
+    // number of cookies as a tie breaker.
+    for (const originInfo of origins) {
+      if (this.toUrl(originInfo.origin).host == 'www.' + siteGroup.etldPlus1) {
+        return originInfo.origin;
+      }
+    }
+    const getMaxStorage = (max, originInfo) => {
+      return (
+          max.usage > originInfo.usage ||
+                  (max.usage == originInfo.usage &&
+                   max.numCookies > originInfo.numCookies) ?
+              max :
+              originInfo);
+    };
+    return origins.reduce(getMaxStorage, origins[0]).origin;
   },
 
   /**

chrome/test/data/webui/settings/site_entry_tests.js

@@ -240,4 +240,48 @@ suite('SiteEntry', function() {
 
     });
   });
+
+  test('favicon with www.etld+1 chosen for site group', function() {
+    // Clone this object to avoid propagating changes made in this test.
+    const testSiteGroup = JSON.parse(JSON.stringify(TEST_MULTIPLE_SITE_GROUP));
+    testSiteGroup.origins[0].usage = 0;
+    testSiteGroup.origins[1].usage = 1274;
+    testSiteGroup.origins[2].usage = 74622;
+    testElement.siteGroup = testSiteGroup;
+    Polymer.dom.flush();
+    assertEquals(
+        testElement.$.collapseParent.querySelector('site-favicon').url,
+        'https://www.example.com');
+  });
+
+  test('favicon with largest storage chosen for site group', function() {
+    // Clone this object to avoid propagating changes made in this test.
+    const testSiteGroup = JSON.parse(JSON.stringify(TEST_MULTIPLE_SITE_GROUP));
+    testSiteGroup.origins[0].usage = 0;
+    testSiteGroup.origins[1].usage = 1274;
+    testSiteGroup.origins[2].usage = 74622;
+    testSiteGroup.origins[1].origin = 'https://abc.example.com';
+    testElement.siteGroup = testSiteGroup;
+    Polymer.dom.flush();
+    assertEquals(
+        testElement.$.collapseParent.querySelector('site-favicon').url,
+        'https://login.example.com');
+  });
+
+  test('favicon with largest cookies number chosen for site group', function() {
+    // Clone this object to avoid propagating changes made in this test.
+    const testSiteGroup = JSON.parse(JSON.stringify(TEST_MULTIPLE_SITE_GROUP));
+    testSiteGroup.origins[0].usage = 0;
+    testSiteGroup.origins[1].usage = 1274;
+    testSiteGroup.origins[2].usage = 1274;
+    testSiteGroup.origins[0].numCookies = 10;
+    testSiteGroup.origins[1].numCookies = 3;
+    testSiteGroup.origins[2].numCookies = 1;
+    testSiteGroup.origins[1].origin = 'https://abc.example.com';
+    testElement.siteGroup = testSiteGroup;
+    Polymer.dom.flush();
+    assertEquals(
+        testElement.$.collapseParent.querySelector('site-favicon').url,
+        'https://abc.example.com');
+  });
 });