Publish: Make 'Channel' setting persistent.

Per discussion with Tom.

ui/component/publishForm/view.jsx

@@ -66,6 +66,7 @@ type Props = {
   // Add back type
   updatePublishForm: any => void,
   checkAvailability: string => void,
+  onChannelChange: string => void,
 };
 
 function PublishForm(props: Props) {
@@ -89,6 +90,7 @@ function PublishForm(props: Props) {
     publish,
     disabled = false,
     checkAvailability,
+    onChannelChange,
   } = props;
   const TAGS_LIMIT = 5;
   const formDisabled = (!filePath && !editingURI) || publishing;
@@ -144,6 +146,11 @@ function PublishForm(props: Props) {
     }
   }, [name, channel, resolveUri, updatePublishForm, checkAvailability]);
 
+  function handleChannelNameChange(channel) {
+    onChannelChange(channel);
+    updatePublishForm({ channel });
+  }
+
   return (
     <div className="card-stack">
       <PublishFile disabled={disabled || publishing} inProgress={isInProgress} />
@@ -182,7 +189,7 @@ function PublishForm(props: Props) {
           <Card
             actions={
               <React.Fragment>
-                <SelectChannel channel={channel} onChannelChange={channel => updatePublishForm({ channel })} />
+                <SelectChannel channel={channel} onChannelChange={handleChannelNameChange} />
                 <p className="help">
                   {__('This is a username or handle that your content can be found under.')}{' '}
                   {__('Ex. @Marvel, @TheBeatles, @BooksByJoe')}

ui/page/publish/view.jsx

@@ -5,6 +5,7 @@ import Page from 'component/page';
 import Yrbl from 'component/yrbl';
 import LbcSymbol from 'component/common/lbc-symbol';
 import RewardAuthIntro from 'component/rewardAuthIntro';
+import usePersistedState from 'effects/use-persisted-state';
 
 type Props = {
   balance: number,
@@ -14,6 +15,8 @@ type Props = {
 function PublishPage(props: Props) {
   const { balance } = props;
 
+  const [channel, setChannel] = usePersistedState('publish-channel', '');
+
   function scrollToTop() {
     const mainContent = document.querySelector('main');
     if (mainContent) {
@@ -21,6 +24,10 @@ function PublishPage(props: Props) {
     }
   }
 
+  function handleChannelChange(channel) {
+    setChannel(channel);
+  }
+
   return (
     <Page>
       {balance === 0 ? (
@@ -55,7 +62,12 @@ function PublishPage(props: Props) {
           </div>
         </Fragment>
       ) : (
-        <PublishForm scrollToTop={scrollToTop} disabled={balance === 0} />
+        <PublishForm
+          scrollToTop={scrollToTop}
+          disabled={balance === 0}
+          channel={channel}
+          onChannelChange={handleChannelChange}
+        />
       )}
     </Page>
   );