feat: consume theme provided by Page theme provider

plugins/rollbar/src/components/RollbarHome/RollbarHome.tsx

@@ -14,17 +14,23 @@
  * limitations under the License.
  */
 
-import { customPageTheme } from '@backstage/theme';
+import { BackstageTheme } from '@backstage/theme';
+import { useTheme } from '@material-ui/core';
 import React from 'react';
 import { Content, Header, Page } from '@backstage/core';
 import { RollbarProjectTable } from '../RollbarProjectTable/RollbarProjectTable';
 import { useRollbarEntities } from '../../hooks/useRollbarEntities';
 
 export const RollbarHome = () => {
+  const backstageTheme = useTheme<BackstageTheme>();
   const { entities, loading, error } = useRollbarEntities();
 
   return (
-    <Page pageTheme={customPageTheme.pageTheme.tool}>
+    <Page
+      theme={backstageTheme.getPageTheme({
+        themeId: 'tool',
+      })}
+    >
       <Header
         title="Rollbar"
         subtitle="Real-time error tracking & debugging tools for developers"

plugins/rollbar/src/components/RollbarProjectPage/RollbarProjectPage.tsx

@@ -14,17 +14,23 @@
  * limitations under the License.
  */
 
-import { customPageTheme } from '@backstage/theme';
+import { BackstageTheme } from '@backstage/theme';
+import { useTheme } from '@material-ui/core';
 import React from 'react';
 import { Content, Header, HeaderLabel, Page } from '@backstage/core';
 import { useCatalogEntity } from '../../hooks/useCatalogEntity';
 import { RollbarProject } from '../RollbarProject/RollbarProject';
 
 export const RollbarProjectPage = () => {
+  const backstageTheme = useTheme<BackstageTheme>();
   const { entity } = useCatalogEntity();
 
   return (
-    <Page pageTheme={customPageTheme.pageTheme.tool}>
+    <Page
+      theme={backstageTheme.getPageTheme({
+        themeId: 'tool',
+      })}
+    >
       <Header title={entity?.metadata?.name} subtitle="Rollbar Project">
         <HeaderLabel label="Owner" value={entity?.spec?.owner} />
         <HeaderLabel label="Lifecycle" value={entity?.spec?.lifecycle} />