Bug 1310833: Make nsAccessibilityService synchronously query for its MSAA content process ID if the ID is not yet present; r=tbsaunde

MozReview-Commit-ID: 9qZNzmwlBNC

--HG--
extra : rebase_source : c9135cb54dd223aef28189957701199f17d63e46

accessible/base/nsAccessibilityService.cpp

@@ -44,6 +44,7 @@
 
 #ifdef XP_WIN
 #include "mozilla/a11y/Compatibility.h"
+#include "mozilla/dom/ContentChild.h"
 #include "HTMLWin32ObjectAccessible.h"
 #include "mozilla/StaticPtr.h"
 #endif
@@ -1264,10 +1265,23 @@ nsAccessibilityService::Init()
   gAccessibilityService = this;
   NS_ADDREF(gAccessibilityService); // will release in Shutdown()
 
-  if (XRE_IsParentProcess())
+  if (XRE_IsParentProcess()) {
     gApplicationAccessible = new ApplicationAccessibleWrap();
-  else
+  } else {
+#if defined(XP_WIN)
+    dom::ContentChild* contentChild = dom::ContentChild::GetSingleton();
+    MOZ_ASSERT(contentChild);
+    // If we were instantiated by the chrome process, GetMsaaID() will return
+    // a non-zero value and we may safely continue with initialization.
+    if (!contentChild->GetMsaaID()) {
+      // Since we were not instantiated by chrome, we need to synchronously
+      // obtain a MSAA content process id.
+      contentChild->SendGetA11yContentId();
+    }
+#endif // defined(XP_WIN)
+
     gApplicationAccessible = new ApplicationAccessible();
+  }
 
   NS_ADDREF(gApplicationAccessible); // will release in Shutdown()
   gApplicationAccessible->Init();

dom/ipc/ContentChild.cpp

@@ -3284,6 +3284,13 @@ ContentChild::RecvBlobURLUnregistration(const nsCString& aURI)
   return true;
 }
 
+#if defined(XP_WIN) && defined(ACCESSIBILITY)
+bool
+ContentChild::SendGetA11yContentId()
+{
+  return PContentChild::SendGetA11yContentId(&mMsaaID);
+}
+#endif // defined(XP_WIN) && defined(ACCESSIBILITY)
 
 void
 ContentChild::CreateGetFilesRequest(const nsAString& aDirectoryPath,

dom/ipc/ContentChild.h

@@ -645,6 +645,11 @@ public:
   virtual bool
   RecvBlobURLUnregistration(const nsCString& aURI) override;
 
+#if defined(XP_WIN) && defined(ACCESSIBILITY)
+  bool
+  SendGetA11yContentId();
+#endif // defined(XP_WIN) && defined(ACCESSIBILITY)
+
   /**
    * Helper function for protocols that use the GPU process when available.
    * Overrides FatalError to just be a warning when communicating with the

dom/ipc/ContentParent.cpp

@@ -5146,6 +5146,18 @@ ContentParent::RecvUnstoreAndBroadcastBlobURLUnregistration(const nsCString& aUR
   return true;
 }
 
+bool
+ContentParent::RecvGetA11yContentId(uint32_t* aContentId)
+{
+#if defined(XP_WIN32) && defined(ACCESSIBILITY)
+  *aContentId = a11y::AccessibleWrap::GetContentProcessIdFor(ChildID());
+  MOZ_ASSERT(*aContentId);
+  return true;
+#else
+  return false;
+#endif
+}
+
 } // namespace dom
 } // namespace mozilla
 

dom/ipc/ContentParent.h

@@ -552,6 +552,9 @@ public:
   virtual bool
   RecvUnstoreAndBroadcastBlobURLUnregistration(const nsCString& aURI) override;
 
+  virtual bool
+  RecvGetA11yContentId(uint32_t* aContentId) override;
+
   virtual int32_t Pid() const override;
 
   // Use the PHangMonitor channel to ask the child to repaint a tab.

dom/ipc/PContent.ipdl

@@ -1178,6 +1178,8 @@ parent:
     async AccumulateChildHistogram(Accumulation[] accumulations);
     async AccumulateChildKeyedHistogram(KeyedAccumulation[] accumulations);
 
+    sync GetA11yContentId() returns (uint32_t aContentId);
+
 both:
      async AsyncMessage(nsString aMessage, CpowEntry[] aCpows,
                         Principal aPrincipal, ClonedMessageData aData);