Bug 1477610 - Flush layout when reporting the visual viewport size via the Visual Viewport API. r=hiro

Differential Revision: https://phabricator.services.mozilla.com/D29089

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

dom/base/VisualViewport.cpp

@@ -13,6 +13,7 @@
 #include "nsIDocShell.h"
 #include "nsPresContext.h"
 #include "nsRefreshDriver.h"
+#include "DocumentInlines.h"
 
 #define VVP_LOG(...)
 // #define VVP_LOG(...) printf_stderr("VVP: " __VA_ARGS__)
@@ -60,6 +61,14 @@ void VisualViewport::GetEventTargetParent(EventChainPreVisitor& aVisitor) {
 CSSSize VisualViewport::VisualViewportSize() const {
   CSSSize size = CSSSize(0, 0);
 
+  // Flush layout, as that may affect the answer below (e.g. scrollbars
+  // may have appeared, decreasing the available viewport size).
+  RefPtr<const VisualViewport> kungFuDeathGrip(this);
+  if (Document* doc = GetDocument()) {
+    doc->FlushPendingNotifications(FlushType::Layout);
+  }
+
+  // Fetch the pres shell after the layout flush, as it might have destroyed it.
   if (PresShell* presShell = GetPresShell()) {
     if (presShell->IsVisualViewportSizeSet()) {
       size = CSSRect::FromAppUnits(presShell->GetVisualViewportSize());
@@ -121,7 +130,7 @@ double VisualViewport::OffsetTop() const {
   return PageTop() - LayoutViewportOffset().Y();
 }
 
-PresShell* VisualViewport::GetPresShell() const {
+Document* VisualViewport::GetDocument() const {
   nsCOMPtr<nsPIDOMWindowInner> window = GetOwner();
   if (!window) {
     return nullptr;
@@ -132,16 +141,17 @@ PresShell* VisualViewport::GetPresShell() const {
     return nullptr;
   }
 
-  return docShell->GetPresShell();
+  return docShell->GetDocument();
+}
+
+PresShell* VisualViewport::GetPresShell() const {
+  RefPtr<Document> document = GetDocument();
+  return document ? document->GetPresShell() : nullptr;
 }
 
 nsPresContext* VisualViewport::GetPresContext() const {
-  PresShell* presShell = GetPresShell();
-  if (!presShell) {
-    return nullptr;
-  }
-
-  return presShell->GetPresContext();
+  RefPtr<Document> document = GetDocument();
+  return document ? document->GetPresContext() : nullptr;
 }
 
 /* ================= Resize event handling ================= */

dom/base/VisualViewport.h

@@ -28,8 +28,8 @@ class VisualViewport final : public mozilla::DOMEventTargetHelper {
   double OffsetTop() const;
   double PageLeft() const;
   double PageTop() const;
-  double Width() const;
-  double Height() const;
+  MOZ_CAN_RUN_SCRIPT double Width() const;
+  MOZ_CAN_RUN_SCRIPT double Height() const;
   double Scale() const;
   IMPL_EVENT_HANDLER(resize)
   IMPL_EVENT_HANDLER(scroll)
@@ -88,9 +88,10 @@ class VisualViewport final : public mozilla::DOMEventTargetHelper {
  private:
   virtual ~VisualViewport();
 
-  CSSSize VisualViewportSize() const;
+  MOZ_CAN_RUN_SCRIPT CSSSize VisualViewportSize() const;
   CSSPoint VisualViewportOffset() const;
   CSSPoint LayoutViewportOffset() const;
+  Document* GetDocument() const;
   PresShell* GetPresShell() const;
   nsPresContext* GetPresContext() const;
 

testing/web-platform/meta/visual-viewport/viewport-read-size-causes-layout.html.ini

@@ -1,10 +0,0 @@
-[viewport-read-size-causes-layout.html]
-  [Untitled]
-    expected: FAIL
-
-  [viewport-read-size-causes-layout]
-    expected:
-      if (os == "android") and not e10s: PASS
-      if (os == "android") and e10s: PASS
-      FAIL
-

testing/web-platform/meta/visual-viewport/viewport-read-size-in-iframe-causes-layout.html.ini

@@ -1,10 +0,0 @@
-[viewport-read-size-in-iframe-causes-layout.html]
-  [Untitled]
-    expected: FAIL
-
-  [viewport-read-size-in-iframe-causes-layout]
-    expected:
-      if (os == "android") and not e10s: PASS
-      if (os == "android") and e10s: PASS
-      FAIL
-

testing/web-platform/meta/visual-viewport/viewport-scrollbars-cause-resize.html.ini

@@ -1,15 +0,0 @@
-[viewport-scrollbars-cause-resize.html]
-  [Viewport: Scrollbars Cause Resize]
-    expected:
-      if (os == "android") and not e10s: PASS
-      FAIL
-
-  [view size reflects appearance of classic scrollbars]
-    expected:
-      if (os == "android") and not e10s: PASS
-      if (os == "android") and e10s: PASS
-      FAIL
-
-  [Resize event was fired at window.visualViewport if, and only if, scrollbars are classic (i.e. affect flow)]
-    disabled: Bug 1515043
-

testing/web-platform/meta/visual-viewport/viewport-unscaled-size.html.ini

@@ -1,7 +0,0 @@
-[viewport-unscaled-size.html]
-  [visualViewport.width should exclude scrollbar.]
-    expected:
-      if (os == "android") and not e10s: PASS
-      if (os == "android") and e10s: PASS
-      FAIL
-