Bug 1648583: Add GetCurrentTopByBrowserId() to get the BrowsingContext for a tab r=nika

Differential Revision: https://phabricator.services.mozilla.com/D81181

docshell/base/BrowsingContext.cpp

@@ -93,10 +93,30 @@ static LazyLogModule gBrowsingContextLog("BrowsingContext");
 
 typedef nsDataHashtable<nsUint64HashKey, BrowsingContext*> BrowsingContextMap;
 
+// All BrowsingContexts indexed by Id
 static StaticAutoPtr<BrowsingContextMap> sBrowsingContexts;
+// Top-level Content BrowsingContexts only, indexed by BrowserId instead of Id
+static StaticAutoPtr<BrowsingContextMap> sCurrentTopByBrowserId;
+
+static void UnregisterBrowserId(BrowsingContext* aBrowsingContext) {
+  if (!aBrowsingContext->IsTopContent() || !sCurrentTopByBrowserId) {
+    return;
+  }
+
+  // Avoids an extra lookup
+  auto browserIdEntry =
+      sCurrentTopByBrowserId->Lookup(aBrowsingContext->BrowserId());
+  if (browserIdEntry && browserIdEntry.Data() == aBrowsingContext) {
+    browserIdEntry.Remove();
+  }
+}
 
 static void Register(BrowsingContext* aBrowsingContext) {
   sBrowsingContexts->Put(aBrowsingContext->Id(), aBrowsingContext);
+  if (aBrowsingContext->IsTopContent()) {
+    sCurrentTopByBrowserId->Put(aBrowsingContext->BrowserId(),
+                                aBrowsingContext);
+  }
 
   aBrowsingContext->Group()->Register(aBrowsingContext);
 }
@@ -134,7 +154,9 @@ WindowContext* BrowsingContext::GetTopWindowContext() {
 void BrowsingContext::Init() {
   if (!sBrowsingContexts) {
     sBrowsingContexts = new BrowsingContextMap();
+    sCurrentTopByBrowserId = new BrowsingContextMap();
     ClearOnShutdown(&sBrowsingContexts);
+    ClearOnShutdown(&sCurrentTopByBrowserId);
   }
 }
 
@@ -146,6 +168,12 @@ already_AddRefed<BrowsingContext> BrowsingContext::Get(uint64_t aId) {
   return do_AddRef(sBrowsingContexts->Get(aId));
 }
 
+/* static */
+already_AddRefed<BrowsingContext> BrowsingContext::GetCurrentTopByBrowserId(
+    uint64_t aBrowserId) {
+  return do_AddRef(sCurrentTopByBrowserId->Get(aBrowserId));
+}
+
 /* static */
 already_AddRefed<BrowsingContext> BrowsingContext::GetFromWindow(
     WindowProxyHolder& aProxy) {
@@ -657,6 +685,7 @@ void BrowsingContext::Detach(bool aFromIPC) {
   }
 
   mGroup->Unregister(this);
+  UnregisterBrowserId(this);
   mIsDiscarded = true;
 
   if (XRE_IsParentProcess()) {
@@ -1061,6 +1090,7 @@ BrowsingContext::~BrowsingContext() {
   if (sBrowsingContexts) {
     sBrowsingContexts->Remove(Id());
   }
+  UnregisterBrowserId(this);
 }
 
 nsISupports* BrowsingContext::GetParentObject() const {
@@ -1483,6 +1513,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(BrowsingContext)
   if (sBrowsingContexts) {
     sBrowsingContexts->Remove(tmp->Id());
   }
+  UnregisterBrowserId(tmp);
 
   if (tmp->GetIsPopupSpam()) {
     PopupBlocker::UnregisterOpenPopupSpam();

docshell/base/BrowsingContext.h

@@ -107,7 +107,8 @@ class WindowProxyHolder;
   FIELD(FeaturePolicy, RefPtr<mozilla::dom::FeaturePolicy>)                  \
   /* See nsSandboxFlags.h for the possible flags. */                         \
   FIELD(SandboxFlags, uint32_t)                                              \
-  /* A unique identifier for the browser element that is hosting this        \
+  /* A non-zero unique identifier for the browser element that is hosting    \
+   * this                                                                    \
    * BrowsingContext tree. Every BrowsingContext in the element's tree will  \
    * return the same ID in all processes and it will remain stable           \
    * regardless of process changes. When a browser element's frameloader is  \
@@ -182,6 +183,9 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
   static already_AddRefed<BrowsingContext> Get(GlobalObject&, uint64_t aId) {
     return Get(aId);
   }
+  // Look up the top-level BrowsingContext by BrowserID.
+  static already_AddRefed<BrowsingContext> GetCurrentTopByBrowserId(
+      uint64_t aBrowserId);
 
   static already_AddRefed<BrowsingContext> GetFromWindow(
       WindowProxyHolder& aProxy);
@@ -316,6 +320,7 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
   bool IsInSubtreeOf(BrowsingContext* aContext);
 
   bool IsContentSubframe() const { return IsContent() && IsFrame(); }
+  // non-zero
   uint64_t Id() const { return mBrowsingContextId; }
 
   BrowsingContext* GetParent() const;