File uploads using Dropbox.

(imported from commit c552133fc7025eca526fbfef24fd544260d7111b)

static/js/feature_flags.js

@@ -7,6 +7,7 @@ exports.mark_read_at_bottom = page_params.staging;
 exports.summarize_read_while_narrowed = page_params.staging;
 exports.twenty_four_hour_time = _.contains([],
                                   page_params.email);
+exports.dropbox_integration = page_params.staging || _.contains(['dropbox.com'], page_params.domain);
 return exports;
 
 }());

static/js/ui.js

@@ -1096,6 +1096,10 @@ $(function () {
     if (window.XMLHttpRequest && (new XMLHttpRequest()).upload) {
         $("#compose #attach_files").removeClass("notdisplayed");
     }
+    if (feature_flags.dropbox_integration && Dropbox.isBrowserSupported()) {
+        $("#compose #attach_dropbox_files").removeClass("notdisplayed");
+    }
+
 
     // Event bindings for "Compose" pane
 
@@ -1107,6 +1111,24 @@ $(function () {
         $("#compose #file_input").trigger("click");
     } );
 
+    $("#compose").on("click", "#attach_dropbox_files", function (e) {
+        e.preventDefault();
+        var options = {
+            // Required. Called when a user selects an item in the Chooser.
+            success: function (files) {
+                var textbox = $("#new_message_content");
+                var links = _.map(files, function (file) { return '[' + file.name + '](' + file.link +')'; })
+                             .join(' ') + ' ';
+                textbox.val(textbox.val() + links);
+
+            },
+            // Optional. A value of false (default) limits selection to a single file, while
+            // true enables multiple file selection.
+            multiselect: true
+        };
+        Dropbox.choose(options);
+    });
+
     $("#subscriptions_table").on("mouseover", ".subscription_header", function (e) {
         $(this).addClass("active");
     });