Implement WebVR presentation pausing for VR Shell Menu Mode

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 1480df6785b9b4e392e0ccdfd209e937ac9dddc1..2eab7ee317878a31a835725a794684c32a328672 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -69,6 +69,7 @@ VRDisplay::VRDisplay(NavigatorVR* navigatorVR)
       m_depthNear(0.01),
       m_depthFar(10000.0),
       m_fullscreenCheckTimer(this, &VRDisplay::onFullscreenCheck),
+      m_contextGL(nullptr),
       m_animationCallbackRequested(false),
       m_inAnimationFrame(false) {}
 
@@ -110,6 +111,9 @@ void VRDisplay::disconnected() {
 bool VRDisplay::getFrameData(VRFrameData* frameData) {
   updatePose();
 
+  if (!m_framePose)
+    return false;
+
   if (!frameData)
     return false;
 
@@ -132,6 +136,10 @@ VRPose* VRDisplay::getPose() {
 }
 
 void VRDisplay::updatePose() {
+  if (m_displayBlurred) {
+    m_framePose = nullptr;

[dcheng, 2016/11/08 23:05:45]

Out of curiosity, why don't we just clear this in onDisplayBlur()?

VRDisplay seems like it's a state machine, so if it's possible to add some more
comments about how the different parts interact, that would help readability.
For someone who's not familiar with the WebVR spec, it can be difficult to
follow the flow of logic.

(Comments and/or pointers to the spec in the implementation can be done in a
followup though)

[mthiesse, 2016/11/10 22:14:10]

I clear it in updatePose simply for code clarity. The spec says to return a null
pose when the display is blurred.

I'll add a few comments for the parts I touched. I'll leave it to bajones@ to
improve readability on the rest, as I myself am not very familiar with spec and
added these changes on his request.

+    return;
+  }
   if (m_canUpdateFramePose) {
     m_framePose = controller()->getPose(m_displayId);
     if (m_isPresenting)
@@ -174,11 +182,34 @@ void VRDisplay::cancelAnimationFrame(int id) {
   m_scriptedAnimationController->cancelCallback(id);
 }
 
+void VRDisplay::onDisplayBlur() {
+  m_displayBlurred = true;
+  m_navigatorVR->fireVrDisplayOnBlur(this);
+}
+
+void VRDisplay::onDisplayFocus() {
+  m_displayBlurred = false;
+  // Restart our internal doc requestAnimationFrame callback, if it fired while
+  // the display was blurred.
+  // TODO(bajones): Don't use doc->requestAnimationFrame() at all. Animation
+  // frames should be tied to the presenting VR display (e.g. should be serviced
+  // by GVR library callbacks on Android), and not the doc frame rate.
+  if (!m_animationCallbackRequested) {
+    Document* doc = m_navigatorVR->document();
+    if (!doc)
+      return;
+    doc->requestAnimationFrame(new VRDisplayFrameRequestCallback(this));
+  }
+  m_navigatorVR->fireVrDisplayOnFocus(this);
+}
+
 void VRDisplay::serviceScriptedAnimations(double monotonicAnimationStartTime) {
   if (!m_scriptedAnimationController)
     return;
   AutoReset<bool> animating(&m_inAnimationFrame, true);
   m_animationCallbackRequested = false;
+  if (m_displayBlurred)
+    return;
   m_scriptedAnimationController->serviceScriptedAnimations(
       monotonicAnimationStartTime);
 }