Saves computed styles in the state

Resolves brave#9149

Auditors:

Test Plan:

app/browser/reducers/windowsReducer.js

@@ -66,6 +66,9 @@ const windowsReducer = (state, action, immutableAction) => {
     case windowConstants.WINDOW_SHOULD_OPEN_DEV_TOOLS:
       windows.openDevTools(action.get('windowId'))
       break
+    case appConstants.APP_WINDOW_COMPUTED_STYLES:
+      state = windowState.updateComputedStyles(state, action)
+      break
   }
   return state
 }

app/common/constants/computedStyles.js

@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const computedStyles = {
+  'bookmark-item': [
+    'max-width',
+    'padding'
+  ]
+}
+
+module.exports = computedStyles

app/common/state/windowState.js

@@ -148,6 +148,13 @@ const api = {
     return state.set('windows', windows.delete(index).insert(index, windowValue))
   },
 
+  updateComputedStyles: (state, action) => {
+    const windowIndex = api.getWindowIndexByWindowId(state, action.get('windowId'))
+    return state.mergeIn(['windows', windowIndex], {
+      computedStyles: action.get('values')
+    })
+  },
+
   getWindows: (state) => {
     state = validateState(state)
     return state.get('windows')

app/renderer/components/window.js

@@ -93,6 +93,10 @@ class Window extends React.Component {
 
   componentDidMount () {
     appActions.windowReady(getCurrentWindowId())
+
+    const root = window.getComputedStyle(document.querySelector(':root'))
+    const maxWidth = Number.parseInt(root.getPropertyValue('--bookmark-item-max-width'), 10)
+    appActions.updateComputedStyles(getCurrentWindowId(), maxWidth)
   }
 
   componentWillUnmount () {

js/actions/appActions.js

@@ -1411,6 +1411,14 @@ const appActions = {
     dispatch({
       actionType: appConstants.APP_UPDATE_LOG_OPENED
     })
+  },
+
+  updateComputedStyles: function (windowId, values) {
+    dispatch({
+      actionType: appConstants.APP_WINDOW_COMPUTED_STYLES,
+      windowId,
+      values
+    })
   }
 
 }

js/constants/appConstants.js

@@ -131,7 +131,8 @@ const appConstants = {
   APP_REMOVE_PASSWORD: _, /** @param {Object} passwordDetail */
   APP_REMOVE_PASSWORD_SITE: _, /** @param {Object} passwordDetail */
   APP_CLEAR_PASSWORDS: _,
-  APP_UPDATE_LOG_OPENED: _
+  APP_UPDATE_LOG_OPENED: _,
+  APP_WINDOW_COMPUTED_STYLES: _
 }
 
 module.exports = mapValuesByKeys(appConstants)