Bug 1697441 - Remove unused SetTabId, r=farre

Differential Revision: https://phabricator.services.mozilla.com/D107802

dom/ipc/BrowserChild.cpp

@@ -2957,13 +2957,6 @@ BrowserChild::GetTabId(uint64_t* aId) {
   return NS_OK;
 }
 
-void BrowserChild::SetTabId(const TabId& aTabId) {
-  MOZ_ASSERT(mUniqueId == 0);
-
-  mUniqueId = aTabId;
-  NestedBrowserChildMap()[mUniqueId] = this;
-}
-
 NS_IMETHODIMP
 BrowserChild::GetChromeOuterWindowID(uint64_t* aId) {
   *aId = ChromeOuterWindowID();

dom/ipc/BrowserChild.h

@@ -763,8 +763,6 @@ class BrowserChild final : public nsMessageManagerScriptExecutor,
 
   bool HasValidInnerSize();
 
-  void SetTabId(const TabId& aTabId);
-
   ScreenIntRect GetOuterRect();
 
   void SetUnscaledInnerSize(const CSSSize& aSize) {