Bug 1510569 - Only forward nsIWebProgress events to the BrowserParent after the WebProgressChild has loaded r=kmag,mconley

Before the WebProgress event handlers started migrating to C++, the parent
process would only receive WebProgress events after the child process had
finished loading the WebProgressChild script. Now that listeners are registered
much earlier (before the BrowserChild has finished setting up its frame
scripts), the BrowserParent would receive WebProgress events that were
heretofore not received unless the BrowserChild was *very* careful about when
it sent the IPC messages.

However, even while being very careful, the OnStateChange event handler would
always fire events for initial about:blank loads that break a lot of unit
tests. Before porting that event, we are now ensuring that the WebProgressChild
has finished loading before the BrowserChild will send IPC messages for these
events to the BrowserParent.

Differential Revision: https://phabricator.services.mozilla.com/D30252

--HG--
extra : moz-landing-system : lando

dom/interfaces/base/nsIBrowserChild.idl

@@ -40,5 +40,13 @@ interface nsIBrowserChild : nsISupports
 
   [noscript, notxpcom] void beforeUnloadAdded();
   [noscript, notxpcom] void beforeUnloadRemoved();
-};
 
+  /**
+   * Tell the nsIBrowserChild that it should begin sending its nsIWebProgress
+   * events to its nsIBrowserParent.
+   *
+   * This should be called once the frame script for the nsIBrowserChild has
+   * loaded.
+   */
+  void beginSendingWebProgressEventsToParent();
+};

dom/ipc/BrowserChild.cpp

@@ -394,22 +394,22 @@ BrowserChild::BrowserChild(ContentChild* aManager, const TabId& aTabId,
       mDidLoadURLInit(false),
       mAwaitingLA(false),
       mSkipKeyPress(false),
-      mLayersObserverEpoch {
-  1
-}
+      mLayersObserverEpoch{1},
 #if defined(XP_WIN) && defined(ACCESSIBILITY)
-, mNativeWindowHandle(0)
+      mNativeWindowHandle(0),
 #endif
 #if defined(ACCESSIBILITY)
-      ,
-    mTopLevelDocAccessibleChild(nullptr)
+      mTopLevelDocAccessibleChild(nullptr),
 #endif
-        ,
-    mPendingDocShellIsActive(false), mPendingDocShellReceivedMessage(false),
-    mPendingRenderLayers(false),
-    mPendingRenderLayersReceivedMessage(false), mPendingLayersObserverEpoch{0},
-    mPendingDocShellBlockers(0), mCancelContentJSEpoch(0),
-    mWidgetNativeData(0) {
+      mShouldSendWebProgressEventsToParent(false),
+      mPendingDocShellIsActive(false),
+      mPendingDocShellReceivedMessage(false),
+      mPendingRenderLayers(false),
+      mPendingRenderLayersReceivedMessage(false),
+      mPendingLayersObserverEpoch{0},
+      mPendingDocShellBlockers(0),
+      mCancelContentJSEpoch(0),
+      mWidgetNativeData(0) {
   mozilla::HoldJSObjects(this);
 
   nsWeakPtr weakPtrThis(do_GetWeakReference(
@@ -3453,6 +3453,11 @@ void BrowserChild::BeforeUnloadRemoved() {
   }
 }
 
+NS_IMETHODIMP BrowserChild::BeginSendingWebProgressEventsToParent() {
+  mShouldSendWebProgressEventsToParent = true;
+  return NS_OK;
+}
+
 mozilla::dom::TabGroup* BrowserChild::TabGroup() { return mTabGroup; }
 
 nsresult BrowserChild::GetHasSiblings(bool* aHasSiblings) {
@@ -3478,7 +3483,7 @@ NS_IMETHODIMP BrowserChild::OnProgressChange(nsIWebProgress* aWebProgress,
                                              int32_t aMaxSelfProgress,
                                              int32_t aCurTotalProgress,
                                              int32_t aMaxTotalProgress) {
-  if (!IPCOpen()) {
+  if (!IPCOpen() || !mShouldSendWebProgressEventsToParent) {
     return NS_OK;
   }
 
@@ -3507,7 +3512,7 @@ NS_IMETHODIMP BrowserChild::OnStatusChange(nsIWebProgress* aWebProgress,
                                            nsIRequest* aRequest,
                                            nsresult aStatus,
                                            const char16_t* aMessage) {
-  if (!IPCOpen()) {
+  if (!IPCOpen() || !mShouldSendWebProgressEventsToParent) {
     return NS_OK;
   }
 
@@ -3534,7 +3539,7 @@ NS_IMETHODIMP BrowserChild::OnSecurityChange(nsIWebProgress* aWebProgress,
 NS_IMETHODIMP BrowserChild::OnContentBlockingEvent(nsIWebProgress* aWebProgress,
                                                    nsIRequest* aRequest,
                                                    uint32_t aEvent) {
-  if (!IPCOpen()) {
+  if (!IPCOpen() || !mShouldSendWebProgressEventsToParent) {
     return NS_OK;
   }
 

dom/ipc/BrowserChild.h

@@ -915,6 +915,8 @@ class BrowserChild final : public BrowserChildBase,
 #endif
   bool mCoalesceMouseMoveEvents;
 
+  bool mShouldSendWebProgressEventsToParent;
+
   // In some circumstances, a DocShell might be in a state where it is
   // "blocked", and we should not attempt to change its active state or
   // the underlying PresShell state until the DocShell becomes unblocked.

toolkit/content/browser-child.js

@@ -8,6 +8,9 @@ const {WebProgressChild} = ChromeUtils.import("resource://gre/modules/WebProgres
 
 this.WebProgress = new WebProgressChild(this);
 
+// This is a method of nsIBrowserChild.
+this.beginSendingWebProgressEventsToParent();
+
 addEventListener("DOMTitleChanged", function(aEvent) {
   if (!aEvent.isTrusted || aEvent.target.defaultView != content)
     return;