Never create pinned tab duplicates

This could happen on slow machine startups when there were multiple state changes before pinned tabs were added

Fix #1508

Auditors: @diracdeltas

CHANGELOG.md

@@ -8,14 +8,15 @@
 - Added show only favicon option to the bookmarks toolbar. ([#1657](https://github.com/brave/browser-laptop/issues/1657))
 - Added bookmark tooltips. ([#1848](https://github.com/brave/browser-laptop/issues/1848))
 - Added folder icons when using bookmark toolbar favicons. ([#1469](https://github.com/brave/browser-laptop/issues/1469))
-- Added application icon in Ubuntu ([#1282](https://github.com/brave/browser-laptop/issues/1282))
+- Added application icon in Ubuntu. ([#1282](https://github.com/brave/browser-laptop/issues/1282))
 - Expose chrome.runtime for better site compat mainly for Google drive. ([#1948](https://github.com/brave/browser-laptop/pull/1948))
 - Fixed processes sometimes not quitting. ([#1756](https://github.com/brave/browser-laptop/issues/1756))
 - Fixed Windows taskbar grouping. ([#156](https://github.com/brave/browser-laptop/issues/156))
-- Fixed whitescreen which could happen when dragging and dropping ([#1891](https://github.com/brave/browser-laptop/issues/1891))
-- Fixed bookmark items middle click to open in a new tab on Windows 10 ([#1724](https://github.com/brave/browser-laptop/issues/1724))
+- Fixed whitescreen which could happen when dragging and dropping. ([#1891](https://github.com/brave/browser-laptop/issues/1891))
+- Fixed bookmark items middle click to open in a new tab on Windows 10. ([#1724](https://github.com/brave/browser-laptop/issues/1724))
 - Fixed redownloading files on session restore ([#1219](https://github.com/brave/browser-laptop/issues/1219))
-- Upgrade to HTTPS Everywhere definitions for 5.1.9 ([#1692](https://github.com/brave/browser-laptop/issues/1692))
+- Fixed pinned tabs sometimes duplicating. ([#1508](https://github.com/brave/browser-laptop/issues/1508))
+- Upgrade to HTTPS Everywhere definitions for 5.1.9. ([#1692](https://github.com/brave/browser-laptop/issues/1692))
 - Upgrade to libchromiumcontent 51.0.2704.63. ([#1405](https://github.com/brave/browser-laptop/issues/1405))
 - Upgrade to Electron 1.2.0. ([#1968])([#1968](https://github.com/brave/browser-laptop/issues/1968))
 - Upgrade to Node 6.1. ([#1969])([#1969](https://github.com/brave/browser-laptop/issues/1969))

js/state/frameStateUtil.js

@@ -179,12 +179,23 @@ function addFrame (frames, frameOpts, newKey, partitionNumber, activeFrameKey) {
   const navbarFocus = activeFrameKey === newKey &&
                       url === config.defaultUrl &&
                       frameOpts.delayedLoadUrl === undefined
+  const location = frameOpts.delayedLoadUrl || url // page url
+
+  // Only add pin requests if it's not already added
+  if (frameOpts.isPinned) {
+    const alreadyPinnedFrameProps = frames.find((frame) =>
+      frame.get('pinnedLocation') === location && frame.get('partitionNumber') === partitionNumber)
+    if (alreadyPinnedFrameProps) {
+      return {}
+    }
+  }
+
   const frame = Immutable.fromJS({
     zoomLevel: config.zoom.defaultValue,
     audioMuted: false, // frame is muted
     canGoBack: false,
     canGoForward: false,
-    location: frameOpts.delayedLoadUrl || url, // page url
+    location,
     aboutDetails: undefined,
     src: url, // what the iframe src should be
     tabId: -1,