crostini: Fix a race in setting the disk slider value.

The max value gets set automatically when we set the ticks on the
slider, but if the observer on slider ticks changing fires after the
observer on value changing, then the value gets clamped to the old max
meaning even if the user has a larger disk, we'll start the slider off
at tick 100. To fix this we explicitly set max, to ensure it's set to
the right value when the clamping happens.

Bug: chromium:1139722
Test: Manual
Change-Id: Ic35d84ce17febdf83ae607e12e0288aa669d55aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2497720Reviewed-by: David Munro <davidmunro@google.com>
Reviewed-by: calamity <calamity@chromium.org>
Auto-Submit: David Munro <davidmunro@google.com>
Commit-Queue: calamity <calamity@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821112}

chrome/browser/resources/settings/chromeos/crostini_page/crostini_disk_resize_dialog.html

@@ -54,7 +54,7 @@
             <div hidden="[[isLowSpaceAvailable_]]" id="recommended-size">
               $i18n{crostiniDiskResizeRecommended}
             </div>
-            <div hidden="[[!isLowSpaceAvailable_]]" 
+            <div hidden="[[!isLowSpaceAvailable_]]"
                 id="recommended-size-warning">
               <iron-icon id="warningIcon" icon="cr:warning"></iron-icon>
               $i18n{crostiniDiskResizeRecommendedWarning}
@@ -63,7 +63,7 @@
           <div id="resize-block">
             <cr-slider id="diskSlider" pin="true"
                 value="[[defaultDiskSizeTick_]]" ticks="[[diskSizeTicks_]]"
-                disabled="[[resizing_]]">
+                disabled="[[resizing_]]" max="[[maxDiskSizeTick_]]">
             </cr-slider>
             <div id="disk-labels" aria-hidden="true">
               <div id="label-begin">[[minDiskSize_]]</div>

chrome/browser/resources/settings/chromeos/crostini_page/crostini_disk_resize_dialog.js

@@ -55,6 +55,11 @@ Polymer({
       type: Number,
     },
 
+    /** @private */
+    maxDiskSizeTick_: {
+      type: Number,
+    },
+
     /** @private */
     isLowSpaceAvailable_: {
       type: Boolean,
@@ -118,6 +123,7 @@ Polymer({
               } else {
                 this.displayState_ = DisplayState.RESIZE;
 
+                this.maxDiskSizeTick = diskInfo.ticks.length - 1;
                 this.defaultDiskSizeTick_ = diskInfo.defaultIndex;
                 this.diskSizeTicks_ = diskInfo.ticks;
                 this.minDiskSize_ = diskInfo.ticks[0].label;