[Nearby] Expand share target list width

Expand share target list width to 200px. Simplify the margins/padding by
removing some of the unnecessary interstital margins on the preview and
list elements and instead putting padding on the main content div.
Change the top margin on the #process-row to 24px to match spec.

Screenshot: https://screenshot.googleplex.com/6Vs8tWVZypxn3Lk.png

Fixed: 1145023
Change-Id: If1cecd192623e5edb638e44190949bf194625108
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593922
Commit-Queue: Curt Clemens <cclem@google.com>
Reviewed-by: James Vecore <vecore@google.com>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837397}

chrome/browser/resources/nearby_share/nearby_discovery_page.html

@@ -13,6 +13,7 @@
     flex-direction: column;
     flex-grow: 1;
     overflow: hidden;
+    padding: 0 32px;
     position: relative;
   }
 
@@ -21,22 +22,13 @@
     display: block;
     margin-top: 12px;
     overflow: auto;
-    padding-inline-end:  var(--nearby-page-space-large-inline);
-    padding-inline-start:  var(--nearby-page-space-large-inline);
-    width: 191px;
-  }
-
-  nearby-preview {
-    margin-inline-end:  var(--nearby-page-space-large-inline);
-    margin-inline-start:  var(--nearby-page-space-large-inline);
+    width: 200px;
   }
 
   #errorSection {
     align-items: flex-start;
     display: flex;
     flex-direction: row;
-    margin-inline-end:  var(--nearby-page-space-inline);
-    margin-inline-start: var(--nearby-page-space-inline);
     padding: 8px;
   }
 
@@ -74,9 +66,6 @@
     font-size: 9px;
     line-height: 12px;
     margin-block-end: 8px;
-    margin-inline-end:  var(--nearby-page-space-inline);
-    margin-inline-start: var(--nearby-page-space-inline);
-    padding: 0 8px;
   }
 
   #helpText {
@@ -101,7 +90,7 @@
     flex-grow: 1;
     justify-content: space-between;
     margin-block-end: 24px;
-    margin-block-start: 8px;
+    margin-block-start: 24px;
     overflow: hidden;
   }