scheduler: Detect load RAIL mode

third_party/WebKit/Source/core/paint/PaintTiming.cpp

Index: third_party/WebKit/Source/core/paint/PaintTiming.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintTiming.cpp b/third_party/WebKit/Source/core/paint/PaintTiming.cpp
index f87085b838c3eeaf5de00e7bed4e77de66bd05c9..f7e7ddd5dececb71047ce14398e71c2ec7e81e3a 100644
--- a/third_party/WebKit/Source/core/paint/PaintTiming.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintTiming.cpp
@@ -5,8 +5,11 @@
 #include "core/paint/PaintTiming.h"
 
 #include "core/dom/Document.h"
+#include "core/frame/FrameView.h"
+#include "core/frame/LocalFrame.h"
 #include "core/loader/DocumentLoader.h"
 #include "platform/tracing/TraceEvent.h"
+#include "public/platform/WebFrameScheduler.h"
 
 namespace blink {
 
@@ -65,6 +68,19 @@ void PaintTiming::markFirstImagePaint() {
   notifyPaintTimingChanged();
 }
 
+void PaintTiming::markFirstMeaningfulPaintCandidate() {
+  // The first meaningful paint candidate can be reported very early, even
+  // before the first contentful paint. To cut down on false positives, we only
+  // report the first meaningful paint candidate after the first contentful
+  // paint.
+  if (!m_firstContentfulPaint)

[Kunihiko Sakamoto, 2016/10/13 08:01:34]

Within a single paint phase, this runs after
PaintTiming::setFirstContentfulPaint(). So this won't skip FCP if it is a FMP
candidate. Is that OK?

[Sami, 2016/10/13 08:23:59]

Good point. Perhaps the thing to do is to ignore the first FMP candidate after
FCP with the theory that it is usually the FCP itself.

[Kunihiko Sakamoto, 2016/10/13 08:38:46]

Yeah, I think patch set 9 would work.

+    return;
+  if (m_document->frame() && m_document->frame()->view() &&
+      !m_document->frame()->view()->parent()) {
+    m_document->frame()->frameScheduler()->onFirstMeaningfulPaint();
+  }
+}
+
 void PaintTiming::setFirstMeaningfulPaint(double stamp) {
   DCHECK_EQ(m_firstMeaningfulPaint, 0.0);
   m_firstMeaningfulPaint = stamp;