Implement <video controls> dodging for text track layout

Source/core/layout/LayoutMedia.cpp

Index: Source/core/layout/LayoutMedia.cpp
diff --git a/Source/core/layout/LayoutMedia.cpp b/Source/core/layout/LayoutMedia.cpp
index 8b960ab7c012b658458db01c46fe972445023594..2078e21c7484d273ee76690c66822e95e6939753 100644
--- a/Source/core/layout/LayoutMedia.cpp
+++ b/Source/core/layout/LayoutMedia.cpp
@@ -28,6 +28,8 @@
 #include "core/layout/LayoutMedia.h"
 
 #include "core/html/HTMLMediaElement.h"
+#include "core/html/shadow/MediaControls.h"
+#include "core/layout/LayoutTextTrackContainer.h"
 #include "core/layout/LayoutView.h"
 
 namespace blink {
@@ -55,19 +57,40 @@ void LayoutMedia::layout()
 
     LayoutSize newSize = contentBoxRect().size();
 
-    LayoutState state(*this, locationOffset());
-
-    for (LayoutObject* child = m_children.firstChild(); child; child = child->nextSibling()) {
-        ASSERT(child->node()->isMediaControls() || child->node()->isTextTrackContainer());
+    bool sizeChanged = newSize != oldSize;
 
-        if (newSize == oldSize && !child->needsLayout())
-            continue;
+    LayoutState state(*this, locationOffset());
 
-        LayoutBox* layoutBox = toLayoutBox(child);
-        layoutBox->setLocation(LayoutPoint(borderLeft(), borderTop()) + LayoutSize(paddingLeft(), paddingTop()));
-        layoutBox->style()->setHeight(Length(newSize.height(), Fixed));
-        layoutBox->style()->setWidth(Length(newSize.width(), Fixed));
-        layoutBox->forceLayout();
+    // Iterate the children in reverse order so that the media controls are laid
+    // out before the text track container.
+    IntRect controlsRect;
+#if ENABLE(ASSERT)
+    bool didLayoutTextTrackContainer = false;
+#endif
+    for (LayoutObject* child = m_children.lastChild(); child; child = child->previousSibling()) {

[fs, 2015/03/17 10:27:56]

I think you could also just drop the for-loop entirely and do something like:

RELEASE_ASSERT(onlyTwoChildren(m_children));
LayoutObject* controls = m_children.lastChild();
LayoutObject* textTrackContainer = nullptr;
if (m_children.lastChild() != m_children.firstChild())
    textTrackContainer = m_children.firstChild();

// Layout one and then the other.
...

Or some variant thereof.

+        bool isMediaControls = child->node()->isMediaControls();
+        bool isTextTrackContainer = child->node()->isTextTrackContainer();
+        ASSERT(isMediaControls || isTextTrackContainer);
+
+        if (isTextTrackContainer) {
+#if ENABLE(ASSERT)
+            didLayoutTextTrackContainer = true;
+#endif
+            static_cast<LayoutTextTrackContainer*>(child)->setControlsRect(controlsRect);
+        }
+
+        if (sizeChanged || child->needsLayout()) {
+            LayoutBox* layoutBox = toLayoutBox(child);
+            layoutBox->setLocation(LayoutPoint(borderLeft(), borderTop()) + LayoutSize(paddingLeft(), paddingTop()));
+            layoutBox->style()->setHeight(Length(newSize.height(), Fixed));
+            layoutBox->style()->setWidth(Length(newSize.width(), Fixed));
+            layoutBox->forceLayout();
+        }
+
+        if (isMediaControls) {
+            ASSERT(!didLayoutTextTrackContainer);
+            controlsRect = toMediaControls(child->node())->absoluteRectForTextTracks();
+        }
     }
 
     clearNeedsLayout();