Initial ResizeObserver implementation

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index cff7ed8b8b6b51103211afe344474fb759590101..bc4b3d58da4f1174dd4cab5cd48058e3cb44a6bc 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -26,6 +26,7 @@
 
 #include "core/frame/FrameView.h"
 
+#include "bindings/core/v8/ScriptCallStack.h"

[szager1, 2016/06/02 20:52:41]

There should be a way to eliminate this.  I still don't see why it's necessary,
but if it really is necessary, then probably something needs to be pushed down
into ExecutionContext.

FrameView does not have any javascript bindings, so it's a layering violation to
include binding code here.

[atotic1, 2016/06/08 18:59:21]

Done. I've just pulled master, and the new API no longer requires the stack.

 #include "core/HTMLNames.h"
 #include "core/MediaTypeNames.h"
 #include "core/css/FontFaceSet.h"
@@ -37,6 +38,7 @@
 #include "core/editing/FrameSelection.h"
 #include "core/editing/RenderedPosition.h"
 #include "core/editing/markers/DocumentMarkerController.h"
+#include "core/events/ErrorEvent.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/FrameHost.h"
@@ -71,6 +73,7 @@
 #include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "core/observer/ResizeObserverController.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/FocusController.h"
@@ -2408,6 +2411,35 @@ void FrameView::scheduleVisualUpdateForPaintInvalidationIfNeeded()
     // Otherwise the paint invalidation will be handled in paint invalidation phase of this cycle.
 }
 
+void FrameView::notifyResizeObserver()
+{
+    if (!m_frame->document()->resizeObserverController())
+        return;
+
+    ResizeObserverController& resizeController = m_frame->document()->ensureResizeObserverController();
+
+    if (lifecycle().state() < DocumentLifecycle::LayoutClean)

[szager1, 2016/06/02 20:52:41]

This makes me uneasy.  If you're going to call
updateStyleAndLayoutIfNeededRecursive() before entering this method, then this
should be:

DCHECK(lifecycle().state() >= DocumentLifecycle::LayoutClean);

Basically, we want to enforce a strict invariant that the document is in a
specific state when this method is called.  We don't want to be flexible about
that.

[atotic1, 2016/06/08 18:59:21]

Done.

+        updateStyleAndLayoutIfNeededRecursive();
+
+    size_t resizeNotifyCount = 0;
+
+    while (resizeController.gatherObservations()) {

[szager1, 2016/06/02 20:52:41]

This still doesn't seem right.  What happens to the notifications that are
generated but never delivered because the loop limit is exceeded?  There should
not be undelivered notifications when this method exits.

[atotic1, 2016/06/08 18:59:21]

Done. I've added a clearObservations().

I was clearing observations in gatherObservations(). This is better, the strong
pointers to Element are not being kept an extra cycle.

+        if (++resizeNotifyCount > ResizeObserverController::kRenderLoopLimit) {
+            // report the error and break
+            ErrorEvent * error = ErrorEvent::create("ResizeObserver loop limit exceeded.", "", 0, 0, nullptr);
+            m_frame->document()->reportException(error, 0, nullptr, NotSharableCrossOrigin);
+            break;
+        }
+
+        resizeController.deliverObservations();
+
+        if (lifecycle().state() < DocumentLifecycle::LayoutClean || layoutView()->needsLayout())
+            updateStyleAndLayoutIfNeededRecursive();
+    }
+
+    DCHECK(!layoutView()->needsLayout());
+}
+
 // TODO(leviw): We don't assert lifecycle information from documents in child PluginViews.
 void FrameView::updateLifecyclePhasesInternal(LifeCycleUpdateOption phases)
 {
@@ -2425,6 +2457,9 @@ void FrameView::updateLifecyclePhasesInternal(LifeCycleUpdateOption phases)
     }
 
     updateStyleAndLayoutIfNeededRecursive();
+
+    notifyResizeObserver();
+
     ASSERT(lifecycle().state() >= DocumentLifecycle::LayoutClean);
 
     if (phases == OnlyUpToLayoutClean) {