PDF Viewer update: Select text on pointerup in zoom input.

This makes the behavior of the page input and zoom input
consistent, per UX request.

Bug: None
Change-Id: I8a44057f22971b9a77f0e7cefa91dd82c7e3e8e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2385955
Auto-Submit: dpapad <dpapad@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Reviewed-by: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803230}

chrome/browser/resources/pdf/elements/viewer-page-selector.html

@@ -35,8 +35,8 @@
         margin: 0 var(--page-selector-spacing);
       }
     </style>
-    <input type="text" id="pageselector" value="[[pageNo]]" on-mouseup="select"
-        on-input="onInput_" on-change="pageNoCommitted"
+    <input type="text" id="pageselector" value="[[pageNo]]"
+        on-pointerup="select" on-input="onInput_" on-change="pageNoCommitted"
         aria-label$="$i18n{labelPageNumber}">
     <span id="divider">/</span>
     <span id="pagelength">[[docLength]]</span>

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar-new.html

@@ -151,6 +151,7 @@
           on-click="onZoomOutClick_">
       </cr-icon-button>
       <input type="text" value="100%" on-input="onZoomInput_"
+          on-pointerup="onZoomInputPointerup_"
           on-blur="onZoomInputBlur_">
       </input>
       <cr-icon-button iron-icon="pdf:add" title="$i18n{tooltipZoomIn}"

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar-new.js

@@ -308,6 +308,14 @@ export class ViewerPdfToolbarNewElement extends PolymerElement {
     this.getZoomInput_().value = zoomString;
   }
 
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  onZoomInputPointerup_(e) {
+    /* @type {!HTMLInputElement} */ (e.target).select();
+  }
+
   /** @private */
   onMoreClick_() {
     const anchor =