Implement important sites dialog for desktop.

chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js

Index: chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js
diff --git a/chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js b/chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js
index 5c8d55722aeff98d7b8e3bde1df11083fb4a7bb0..12526ff2c56b7c01d234927d064810a436186e0b 100644
--- a/chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js
+++ b/chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js
@@ -21,6 +21,15 @@ Polymer({
     },
 
     /**
+     * State of this dialog, either "clearBrowsingData" or "importantSites".
+     * @private
+     */
+    dialogState_: {
+      type: String,
+      value: 'clearBrowsingData',
+    },
+
+    /**
      * Results of browsing data counters, keyed by the suffix of
      * the corresponding data type deletion preference, as reported
      * by the C++ side.
@@ -29,7 +38,7 @@ Polymer({
     counters_: {
       type: Object,
       value: {
-        // Will be filled as results are reported.
+          // Will be filled as results are reported.

[dullweber, 2017/04/07 09:39:21]

This formatting by "git cl format --js" seems odd, I would expect the comment to
be indented by 2 spaces. Should I file a clang-format bug?

[dschuyler, 2017/04/07 22:57:34]

I agree that's weird and I would expect a two space indent here.

[dullweber, 2017/04/10 10:59:50]

I submitted a bug for clang-format

       }

[dschuyler, 2017/04/07 22:57:34]

Hey that helps point out another issue that I missed before:
This |value| will be like a class-static value, instead of an instance (object)
value. Unless a class var is really desired (which should have a comment saying
so) this should instead be:

value: function() { return {}; },

So that it will be an instance var.
Here's a demo to illustrate the difference:
http://jsbin.com/gogonufazi/3/edit?html,console,output

[dullweber, 2017/04/10 10:59:50]

Ah, that looks interesting, thanks. I guess the same issue exists with the
default array for importantSites_? I fixed that one too.

     },
 
@@ -60,6 +69,19 @@ Polymer({
       type: Boolean,
       value: false,
     },
+
+    /** @private {!Array<ImportantSite>} */
+    importantSites_: {
+      type: Array,
+      value: [],
+    },
+
+    /** @private */
+    importantSitesFlagEnabled_: {
+      type: Boolean,
+      value: false,
+    },
+
   },
 
   /** @private {settings.ClearBrowsingDataBrowserProxy} */
@@ -82,10 +104,21 @@ Polymer({
         settings.ClearBrowsingDataBrowserProxyImpl.getInstance();
     this.browserProxy_.initialize().then(function() {
       this.$.dialog.showModal();
+      this.browserProxy_.fetchImportantSites().then(
+          this.receiveImportantSites.bind(this));
     }.bind(this));
   },
 
   /**
+   * @param {!ImportantSitesResponse} result
+   * @private
+   */
+  receiveImportantSites: function(result) {
+    this.importantSitesFlagEnabled_ = result.flagEnabled;
+    this.set('importantSites_', result.importantSites);
+  },
+
+  /**
    * Updates the footer to show only those sentences that are relevant to this
    * user.
    * @param {boolean} syncing Whether the user is syncing data.
@@ -114,24 +147,65 @@ Polymer({
   },
 
   /**
+   * @param {string} currentDialogState The current dialog state.
+   * @return {boolean} Whether this is the clear browsing data dialog.
+   * @private
+   */
+  isClearBrowsingDataDialog_: function(currentDialogState) {
+    return currentDialogState == 'clearBrowsingData';
+  },
+
+  /**
+   * @param {string} currentDialogState The current dialog state.
+   * @return {boolean} Whether this is the important sites dialog.
+   * @private
+   */
+  isImportantSitesDialog_: function(currentDialogState) {
+    return currentDialogState == 'importantSites';
+  },
+
+  /** @private */
+  shouldShowImportantSites_: function() {
+    if (this.isImportantSitesDialog_(this.dialogState_))
+      return false;
+    if (!this.importantSitesFlagEnabled_)
+      return false;
+    if (!this.$.cookiesCheckbox.checked && !this.$.cacheCheckbox.checked) {
+      return false;
+    }
+    var haveImportantSites = this.importantSites_.length > 0;
+    chrome.send(
+        'metricsHandler:recordBooleanHistogram',
+        ['History.ClearBrowsingData.ImportantDialogShown', haveImportantSites]);
+    return haveImportantSites;
+  },
+
+  /**
    * Handles the tap on the Clear Data button.
    * @private
    */
   onClearBrowsingDataTap_: function() {
+    if (this.shouldShowImportantSites_()) {
+      this.dialogState_ = 'importantSites';
+      return;
+    }
+
     this.clearingInProgress_ = true;
 
-    this.browserProxy_.clearBrowsingData().then(
-      /**
-       * @param {boolean} shouldShowNotice Whether we should show the notice
-       *     about other forms of browsing history before closing the dialog.
-       */
-      function(shouldShowNotice) {
-        this.clearingInProgress_ = false;
-        this.showHistoryDeletionDialog_ = shouldShowNotice;
-
-        if (!shouldShowNotice)
-          this.$.dialog.close();
-      }.bind(this));
+    this.browserProxy_.clearBrowsingData(this.importantSites_)
+        .then(
+            /**
+             * @param {boolean} shouldShowNotice Whether we should show the
+             * notice about other forms of browsing history before closing the
+             * dialog.
+             */
+            function(shouldShowNotice) {
+              this.clearingInProgress_ = false;
+              this.showHistoryDeletionDialog_ = shouldShowNotice;
+
+              if (!shouldShowNotice)
+                this.$.dialog.close();
+            }.bind(this));
   },
 
   /** @private */