Diagnostics: Remove free memory data point

Bug: 1125150
Test: browser_tests --gtest_filter=DiagnosticsApp*
Change-Id: I8b52ffa0b52c09118bcc1c58c27cebfe6de4c5e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2444049
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813605}

chrome/test/data/webui/chromeos/diagnostics/memory_card_test.js

@@ -62,7 +62,6 @@ suite('MemoryCardTest', () => {
       assertEquals(fakeMemoryUsage[0].total_memory_kib, dataPoints[0].value);
       assertEquals(
           fakeMemoryUsage[0].available_memory_kib, dataPoints[1].value);
-      assertEquals(fakeMemoryUsage[0].free_memory_kib, dataPoints[2].value);
 
       const barChart =
           diagnostics_test_utils.getPercentBarChartElement(memoryElement);

chromeos/components/diagnostics_ui/resources/memory_card.html

@@ -9,9 +9,6 @@
   <data-point slot="body" id="memoryAvailable"
     value="[[memoryUsage_.available_memory_kib]]">
   </data-point>
-  <data-point slot="body" id="memoryFree"
-    value="[[memoryUsage_.free_memory_kib]]">
-  </data-point>
   <!-- TODO(joonbug): Localize once strings are confirmed -->
   <percent-bar-chart slot="body" title="Used memory"
     value="[[getTotalUsedMemory_(memoryUsage_)]]"