Bug 1156160 - Update carets when document becomes visible. r=mtseng

When the user switches back to a tab which has the selection highlight on
the document, call UpdateCarets() to bring the carets back.

MozReview-Commit-ID: LxNoNRl4FHZ

--HG--
extra : rebase_source : f6fdc9b5c646b064bbe1e27456bbeaac063bd04c

layout/base/AccessibleCaretEventHub.cpp

@@ -32,7 +32,8 @@ namespace mozilla {
 #define AC_LOGV(message, ...)                                                  \
   AC_LOGV_BASE("AccessibleCaretEventHub (%p): " message, this, ##__VA_ARGS__);
 
-NS_IMPL_ISUPPORTS(AccessibleCaretEventHub, nsIReflowObserver, nsIScrollObserver,
+NS_IMPL_ISUPPORTS(AccessibleCaretEventHub,
+                  nsIDocumentActivity, nsIReflowObserver, nsIScrollObserver,
                   nsISelectionListener, nsISupportsWeakReference);
 
 // -----------------------------------------------------------------------------
@@ -433,6 +434,12 @@ AccessibleCaretEventHub::Init()
 
   mDocShell = static_cast<nsDocShell*>(docShell);
 
+  nsIDocument* doc = mPresShell->GetDocument();
+  if (doc) {
+    doc->RegisterActivityObserver(
+      NS_ISUPPORTS_CAST(nsIDocumentActivity*, this));
+  }
+
   if (sUseLongTapInjector) {
     mLongTapInjectorTimer = do_CreateInstance("@mozilla.org/timer;1");
   }
@@ -457,6 +464,12 @@ AccessibleCaretEventHub::Terminate()
     docShell->RemoveWeakScrollObserver(this);
   }
 
+  nsIDocument* doc = mPresShell->GetDocument();
+  if (doc) {
+    doc->UnregisterActivityObserver(
+      NS_ISUPPORTS_CAST(nsIDocumentActivity*, this));
+  }
+
   if (mLongTapInjectorTimer) {
     mLongTapInjectorTimer->Cancel();
   }
@@ -701,6 +714,25 @@ AccessibleCaretEventHub::ReflowInterruptible(DOMHighResTimeStamp aStart,
   return Reflow(aStart, aEnd);
 }
 
+void
+AccessibleCaretEventHub::NotifyOwnerDocumentActivityChanged()
+{
+  if (!mInitialized) {
+    return;
+  }
+
+  MOZ_ASSERT(mRefCnt.get() > 1, "Expect caller holds us as well!");
+
+  nsIDocument* doc = mPresShell->GetDocument();
+  if (!doc) {
+    return;
+  }
+
+  if (!doc->Hidden()) {
+    mManager->OnDocumentVisible();
+  }
+}
+
 void
 AccessibleCaretEventHub::AsyncPanZoomStarted()
 {

layout/base/AccessibleCaretEventHub.h

@@ -11,6 +11,7 @@
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WeakPtr.h"
 #include "nsCOMPtr.h"
+#include "nsIDocumentActivity.h"
 #include "nsIFrame.h"
 #include "nsIReflowObserver.h"
 #include "nsIScrollObserver.h"
@@ -60,10 +61,12 @@ class WidgetTouchEvent;
 // Please see the wiki page for more information.
 // https://wiki.mozilla.org/AccessibleCaret
 //
-class AccessibleCaretEventHub : public nsIReflowObserver,
-                                public nsIScrollObserver,
-                                public nsISelectionListener,
-                                public nsSupportsWeakReference
+class AccessibleCaretEventHub
+  : public nsIDocumentActivity
+  , public nsIReflowObserver
+  , public nsIScrollObserver
+  , public nsISelectionListener
+  , public nsSupportsWeakReference
 {
 public:
   explicit AccessibleCaretEventHub(nsIPresShell* aPresShell);
@@ -76,6 +79,7 @@ public:
   void NotifyBlur(bool aIsLeavingDocument);
 
   NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOCUMENTACTIVITY
   NS_DECL_NSIREFLOWOBSERVER
   NS_DECL_NSISELECTIONLISTENER
 

layout/base/AccessibleCaretManager.cpp

@@ -751,6 +751,13 @@ AccessibleCaretManager::OnFrameReconstruction()
   mSecondCaret->EnsureApzAware();
 }
 
+void
+AccessibleCaretManager::OnDocumentVisible()
+{
+  AC_LOG("%s: UpdateCarets()", __FUNCTION__);
+  UpdateCarets();
+}
+
 void
 AccessibleCaretManager::SetLastInputSource(uint16_t aInputSource)
 {

layout/base/AccessibleCaretManager.h

@@ -103,6 +103,10 @@ public:
   // was reconstructed, resulting in the content elements getting cloned.
   virtual void OnFrameReconstruction();
 
+  // Called by AccessibleCaretEventHub to inform us that the document
+  // becomes visible.
+  virtual void OnDocumentVisible();
+
   // Update the manager with the last input source that was observed. This
   // is used in part to determine if the carets should be shown or hidden.
   void SetLastInputSource(uint16_t aInputSource);