[CrOS MultiDevice] Fix a few chrome://multidevice-internals issues

(1) Add a newline at the end of each line when saving logs file.
(2) Show logs in chronological order.
(3) Fix issue which showed "../../" at the start of every filename.

Change-Id: I3c40a4c083d156c70998149a0c61b618767c7fc2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2372600
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Josh Nohle <nohle@chromium.org>
Reviewed-by: Josh Nohle <nohle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801383}

chrome/browser/resources/chromeos/multidevice_internals/log_object.html

@@ -39,6 +39,6 @@
   <div id="item-metadata">
     <span>[[item.time]]</span>
     <div id="flex"></div>
-    <span>[[item.file]]:[[item.line]]</span>
+    <span>[[getFilenameWithLine_(item.file, item.line)]]</span>
   </div>
 </div>

chrome/browser/resources/chromeos/multidevice_internals/log_object.js

@@ -42,4 +42,18 @@ Polymer({
         break;
     }
   },
+
+  /**
+   * @return {string}
+   * @private
+   */
+  getFilenameWithLine_() {
+    if (!this.item) {
+      return '';
+    }
+
+    // The filename is prefixed with "../../", so replace it with "//".
+    let filename = this.item.file.replace('../../', '//');
+    return filename + ':' + this.item.line;
+  },
 });

chrome/browser/resources/chromeos/multidevice_internals/logging_tab.js

@@ -39,7 +39,7 @@ function logToSavedString_(log) {
   // Reduce the file path to just the file name for logging simplification.
   const file = log.file.substring(log.file.lastIndexOf('/') + 1);
 
-  return `[${log.time} ${severity} ${file} (${log.line})] ${log.text}`;
+  return `[${log.time} ${severity} ${file} (${log.line})] ${log.text}\n`;
 }
 
 Polymer({
@@ -124,7 +124,9 @@ Polymer({
    * @return {!Array<string>}
    */
   getSerializedLogStrings_() {
-    return this.logList_.map(logToSavedString_);
+    // Reverse the logs so that the oldest logs appear first and the newest logs
+    // appear last.
+    return this.logList_.map(logToSavedString_).reverse();
   },
 
   /**