Print Preview: Making margin lines draggable.

chrome/browser/resources/print_preview/preview_area.js

Index: chrome/browser/resources/print_preview/preview_area.js
diff --git a/chrome/browser/resources/print_preview/preview_area.js b/chrome/browser/resources/print_preview/preview_area.js
index 88a419230af7e9077574722a1e00611660eea51b..af191ae7c7c1c9ab5ad1711096b910a4ca36c534 100644
--- a/chrome/browser/resources/print_preview/preview_area.js
+++ b/chrome/browser/resources/print_preview/preview_area.js
@@ -24,6 +24,12 @@ cr.define('print_preview', function() {
     //     before a new preview is requested so that the scroll amount can be
     //     restored later.
     this.pageOffset_ = null;
+
+    // @type {print_preview.Rect} A rectangle describing the postion of the
+    // most visible page normalized with respect to the total height and width
+    // of the plugin.
+    this.pageLocationNormalized = null;
+
     this.addEventListeners_();
   }
 
@@ -78,17 +84,19 @@ cr.define('print_preview', function() {
     },
 
     /**
-     * @return {print_preview.Rect} A rectangle describing the postion of the
-     *   most visible page normalized with respect to the total height and width
-     *   of the plugin.
+     * Queries the plugin for the location of the most visible page and updates
+     * |this.pageLocationNormalized|.
      */
-    getPageLocationNormalized: function() {
+    update: function() {
+      if (!this.pdfLoaded_)
+        return;
       var pluginLocation =
           this.pdfPlugin_.getPageLocationNormalized().split(';');
-      return new print_preview.Rect(parseFloat(pluginLocation[0]),
-                                    parseFloat(pluginLocation[1]),
-                                    parseFloat(pluginLocation[2]),
-                                    parseFloat(pluginLocation[3]));
+      this.pageLocationNormalized = new print_preview.Rect(
+          parseFloat(pluginLocation[0]),
+          parseFloat(pluginLocation[1]),
+          parseFloat(pluginLocation[2]),
+          parseFloat(pluginLocation[3]));
     },
 
     /**