Add more WebVR layout tests and fix small issues they found

third_party/WebKit/Source/modules/vr/VRDisplay.cpp

Index: third_party/WebKit/Source/modules/vr/VRDisplay.cpp
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
index b2d9678e3df6bc57f8254ec94587ab0119655b2b..02ec6b377874f2ac0ec9854d5a7d246e4ca57650 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -324,9 +324,9 @@ ScriptPromise VRDisplay::requestPresent(ScriptState* scriptState,
     return promise;
   }
 
-  m_layer = layers[0];
-
-  if (!m_layer.source()) {
+  // If what we were given has an invalid source, need to exit fullscreen with
+  // previous, valid source, so delay m_layer reassignment
+  if (!layers[0].source()) {

[bsheedy, 2017/01/11 22:56:49]

Changed to address https://bugs.chromium.org/p/chromium/issues/detail?id=679952

     forceExitPresent();
     DOMException* exception =
         DOMException::create(InvalidStateError, "Invalid layer source.");
@@ -334,6 +334,7 @@ ScriptPromise VRDisplay::requestPresent(ScriptState* scriptState,
     ReportPresentationResult(PresentationResult::InvalidLayerSource);
     return promise;
   }
+  m_layer = layers[0];
 
   CanvasRenderingContext* renderingContext =
       m_layer.source()->renderingContext();