WebVR compositor bypass via BrowserMain context + mailbox

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 cc8f1038aae5d967f3865cc8b9a1881194dcb3d9..12d0f25d27218fb97324228e44463195c0b2582c 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
@@ -8,13 +8,17 @@
 #include "core/dom/DOMException.h"
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/FrameRequestCallback.h"
-#include "core/dom/Fullscreen.h"
 #include "core/dom/ScriptedAnimationController.h"
 #include "core/dom/TaskRunnerHelper.h"
+#include "core/frame/FrameView.h"
+#include "core/frame/ImageBitmap.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/ConsoleMessage.h"
+#include "core/layout/LayoutView.h"
+#include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/loader/DocumentLoader.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
+#include "gpu/command_buffer/common/mailbox_holder.h"
 #include "modules/EventTargetModules.h"
 #include "modules/vr/NavigatorVR.h"
 #include "modules/vr/VRController.h"
@@ -27,6 +31,7 @@
 #include "modules/webgl/WebGLRenderingContextBase.h"
 #include "platform/Histogram.h"
 #include "platform/UserGestureIndicator.h"
+#include "platform/instrumentation/tracing/TraceEvent.h"
 #include "public/platform/Platform.h"
 #include "wtf/AutoReset.h"
 #include "wtf/Time.h"
@@ -37,10 +42,6 @@ namespace blink {
 
 namespace {
 
-// Magic numbers used to mark valid pose index values encoded in frame
-// data. Must match the magic numbers used in vr_shell.cc.
-static constexpr std::array<uint8_t, 2> kWebVrPosePixelMagicNumbers{{42, 142}};
-
 VREye stringToVREye(const String& whichEye) {
   if (whichEye == "left")
     return VREyeLeft;
@@ -59,12 +60,8 @@ VRDisplay::VRDisplay(NavigatorVR* navigatorVR,
       m_capabilities(new VRDisplayCapabilities()),
       m_eyeParametersLeft(new VREyeParameters()),
       m_eyeParametersRight(new VREyeParameters()),
-      m_fullscreenCheckTimer(
-          TaskRunnerHelper::get(TaskType::UnspecedTimer,
-                                navigatorVR->document()->frame()),
-          this,
-          &VRDisplay::onFullscreenCheck),
       m_display(std::move(display)),
+      m_submit_frame_client_binding(this),
       m_displayClientBinding(this, std::move(request)) {}
 
 VRDisplay::~VRDisplay() {}
@@ -239,17 +236,6 @@ ScriptPromise VRDisplay::requestPresent(ScriptState* scriptState,
     return promise;
   }
 
-  // TODO(mthiesse): Remove fullscreen requirement for presentation. See
-  // crbug.com/687369
-  Document* doc = this->document();
-  if (!doc || !Fullscreen::fullscreenEnabled(*doc)) {
-    DOMException* exception =
-        DOMException::create(InvalidStateError, "Fullscreen is not enabled.");
-    resolver->reject(exception);
-    ReportPresentationResult(PresentationResult::FullscreenNotEnabled);
-    return promise;
-  }
-
   // A valid number of layers must be provided in order to present.
   if (layers.size() == 0 || layers.size() > m_capabilities->maxLayers()) {
     forceExitPresent();
@@ -395,50 +381,9 @@ void VRDisplay::beginPresent() {
     return;
   } else {
     if (m_layer.source().isHTMLCanvasElement()) {
-      HTMLCanvasElement* canvas = m_layer.source().getAsHTMLCanvasElement();
-      // TODO(klausw,crbug.com/655722): Need a proper VR compositor, but
-      // for the moment on mobile we'll just make the canvas fullscreen
-      // so that VrShell can pick it up through the standard (high
-      // latency) compositing path.      auto canvas =
-      // m_layer.source().getAsHTMLCanvasElement();
-      auto inlineStyle = canvas->inlineStyle();
-      if (inlineStyle) {
-        // THREE.js's VREffect sets explicit style.width/height on its rendering
-        // canvas based on the non-fullscreen window dimensions, and it keeps
-        // those unchanged when presenting. Unfortunately it appears that a
-        // fullscreened canvas just gets centered if it has explicitly set a
-        // size smaller than the fullscreen dimensions. Manually set size to
-        // 100% in this case and restore it when exiting fullscreen. This is a
-        // stopgap measure since THREE.js's usage appears legal according to the
-        // WebVR API spec. This will no longer be necessary once we can get rid
-        // of this fullscreen hack.
-        m_fullscreenOrigWidth = inlineStyle->getPropertyValue(CSSPropertyWidth);
-        if (!m_fullscreenOrigWidth.isNull()) {
-          canvas->setInlineStyleProperty(CSSPropertyWidth, "100%");
-        }
-        m_fullscreenOrigHeight =
-            inlineStyle->getPropertyValue(CSSPropertyHeight);
-        if (!m_fullscreenOrigHeight.isNull()) {
-          canvas->setInlineStyleProperty(CSSPropertyHeight, "100%");
-        }
-      } else {
-        m_fullscreenOrigWidth = String();
-        m_fullscreenOrigHeight = String();
-      }
-
-      if (doc) {
-        // Since the callback for requestPresent is asynchronous, we've lost our
-        // UserGestureToken, and need to create a new one to enter fullscreen.
-        gestureIndicator = WTF::wrapUnique(
-            new UserGestureIndicator(DocumentUserGestureToken::create(
-                doc, UserGestureToken::Status::PossiblyExistingGesture)));
-      }
-      Fullscreen::requestFullscreen(*canvas);
-
-      // Check to see if the canvas is still the current fullscreen
-      // element once every 2 seconds.
-      m_fullscreenCheckTimer.startRepeating(2.0, BLINK_FROM_HERE);
-      m_reenteredFullscreen = false;
+      // TODO(klausw,crbug.com/698923): suppress compositor updates
+      // since they aren't needed, they do a fair amount of extra
+      // work.
     } else {
       DCHECK(m_layer.source().isOffscreenCanvas());
       // TODO(junov, crbug.com/695497): Implement OffscreenCanvas presentation
@@ -519,7 +464,8 @@ void VRDisplay::updateLayerBounds() {
   }
 
   m_display->UpdateLayerBounds(m_vrFrameId, std::move(leftBounds),
-                               std::move(rightBounds));
+                               std::move(rightBounds), m_sourceWidth,
+                               m_sourceHeight);
 }
 
 HeapVector<VRLayer> VRDisplay::getLayers() {
@@ -535,6 +481,7 @@ HeapVector<VRLayer> VRDisplay::getLayers() {
 void VRDisplay::submitFrame() {
   if (!m_display)
     return;
+  TRACE_EVENT1("gpu", "submitFrame", "frame", m_vrFrameId);
 
   Document* doc = this->document();
   if (!m_isPresenting) {
@@ -563,42 +510,113 @@ void VRDisplay::submitFrame() {
 
   // No frame Id to write before submitting the frame.
   if (m_vrFrameId < 0) {
-    m_display->SubmitFrame(m_framePose.Clone());
+    // TODO(klausw): There used to be a submitFrame here, but we can't
+    // submit without a frameId and associated pose data. Just drop it.
     return;
   }
 
-  // Write the frame number for the pose used into a bottom left pixel block.
-  // It is read by chrome/browser/android/vr_shell/vr_shell.cc to associate
-  // the correct corresponding pose for submission.
-  auto gl = m_contextGL;
-
-  // We must ensure that the WebGL app's GL state is preserved. We do this by
-  // calling low-level GL commands directly so that the rendering context's
-  // saved parameters don't get overwritten.
-
-  gl->Enable(GL_SCISSOR_TEST);
-  // Use a few pixels to ensure we get a clean color. The resolution for the
-  // WebGL buffer may not match the final rendered destination size, and
-  // texture filtering could interfere for single pixels. This isn't visible
-  // since the final rendering hides the edges via a vignette effect.
-  gl->Scissor(0, 0, 4, 4);
-  gl->ColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
-  // Careful with the arithmetic here. Float color 1.f is equivalent to int 255.
-  // Use the low byte of the index as the red component, and store an arbitrary
-  // magic number in green/blue. This number must match the reading code in
-  // vr_shell.cc. Avoid all-black/all-white.
-  gl->ClearColor((m_vrFrameId & 255) / 255.0f,
-                 kWebVrPosePixelMagicNumbers[0] / 255.0f,
-                 kWebVrPosePixelMagicNumbers[1] / 255.0f, 1.0f);
-  gl->Clear(GL_COLOR_BUFFER_BIT);
-
-  // Set the GL state back to what was set by the WebVR application.
-  m_renderingContext->restoreScissorEnabled();
-  m_renderingContext->restoreScissorBox();
-  m_renderingContext->restoreColorMask();
-  m_renderingContext->restoreClearColor();
-
-  m_display->SubmitFrame(m_framePose.Clone());
+  m_contextGL->Flush();
+  auto elem = m_layer.source();
+
+  // Check if the canvas got resized, if yes send a bounds update.
+  int currentWidth = m_renderingContext->drawingBufferWidth();
+  int currentHeight = m_renderingContext->drawingBufferHeight();
+  if ((currentWidth != m_sourceWidth || currentHeight != m_sourceHeight) &&
+      currentWidth != 0 && currentHeight != 0) {
+    m_sourceWidth = currentWidth;
+    m_sourceHeight = currentHeight;
+    updateLayerBounds();
+  }
+
+  // There's two types of synchronization needed for submitting frames:
+  //
+  // - Before submitting, need to wait for the previous frame to be
+  //   pulled off the transfer surface to avoid lost frames. This
+  //   is currently a compile-time option, normally we always want
+  //   to defer this wait to increase parallelism.
+  //
+  // - After submitting, need to wait for the mailbox to be consumed,
+  //   and must remain inside the execution context while waiting.
+  //   The waitForPreviousTransferToFinish option defers this wait
+  //   until the next frame. That's more efficient, but seems to
+  //   cause wobbly framerates.
+  bool waitForPreviousTransferToFinish =
+      RuntimeEnabledFeatures::webVRExperimentalRenderingEnabled();
+
+  if (waitForPreviousTransferToFinish) {
+    TRACE_EVENT0("gpu", "waitPrevXfer");
+    while (m_pendingSubmitFrame) {
+      if (!m_submit_frame_client_binding.WaitForIncomingMethodCall()) {
+        LOG(ERROR) << "Failed to receive SubmitFrame response";
+        break;
+      }
+    }
+  }
+
+  auto image_ref = m_renderingContext->getImage(
+      PreferAcceleration, SnapshotReasonCreateImageBitmap);
+
+  // Hardware-accelerated rendering should always be texture backed.
+  // I hope nobody is trying to do WebVR with software rendering.
+  DCHECK(image_ref->isTextureBacked());
+
+  // The AcceleratedStaticBitmapImage must be kept alive until the
+  // mailbox is used via createAndConsumeTextureCHROMIUM, the mailbox
+  // itself does not keep it alive. We must keep a reference to the
+  // image until the mailbox was consumed.
+  StaticBitmapImage* staticImage =
+      static_cast<StaticBitmapImage*>(image_ref.get());
+  staticImage->ensureMailbox();
+
+  if (waitForPreviousTransferToFinish) {
+    // Save a reference to the image to keep it alive until next frame,
+    // where we'll wait for the transfer to finish before overwriting
+    // it.
+    m_previousImage = std::move(image_ref);
+  }
+
+  // Wait for the previous render to finish, to avoid losing frames in the
+  // Android Surface / GLConsumer pair. TODO(klausw): make this tunable?
+  // Other devices may have different preferences.
+  {
+    TRACE_EVENT0("gpu", "waitPrevRender");
+    while (m_pendingPreviousFrameRender) {
+      if (!m_submit_frame_client_binding.WaitForIncomingMethodCall()) {
+        LOG(ERROR) << "Failed to receive SubmitFrame response";
+        break;
+      }
+    }
+    TRACE_EVENT_END0("gpu", "waitPrevRender");
+  }
+
+  m_pendingPreviousFrameRender = true;
+  m_pendingSubmitFrame = true;
+  m_display->SubmitFrame(
+      m_vrFrameId,
+      gpu::MailboxHolder(staticImage->mailbox(), staticImage->syncToken(),
+                         GL_TEXTURE_2D),
+      m_submit_frame_client_binding.CreateInterfacePtrAndBind());
+
+  // If we're not deferring the wait for transferring the mailbox,
+  // we need to wait for it now to prevent the image going out of
+  // scope before its mailbox is retrieved.
+  if (!waitForPreviousTransferToFinish) {
+    TRACE_EVENT0("gpu", "waitCurrXfer");
+    while (m_pendingSubmitFrame) {
+      if (!m_submit_frame_client_binding.WaitForIncomingMethodCall()) {
+        LOG(ERROR) << "Failed to receive SubmitFrame response";
+        break;
+      }
+    }
+  }
+}
+
+void VRDisplay::OnSubmitFrameTransferred() {
+  m_pendingSubmitFrame = false;
+}
+
+void VRDisplay::OnSubmitFrameRendered() {
+  m_pendingPreviousFrameRender = false;
 }
 
 Document* VRDisplay::document() {
@@ -636,19 +654,8 @@ void VRDisplay::stopPresenting() {
   if (m_isPresenting) {
     if (!m_capabilities->hasExternalDisplay()) {
       if (m_layer.source().isHTMLCanvasElement()) {
-        auto canvas = m_layer.source().getAsHTMLCanvasElement();
-        Fullscreen::fullyExitFullscreen(canvas->document());
-        m_fullscreenCheckTimer.stop();
-        if (!m_fullscreenOrigWidth.isNull()) {
-          canvas->setInlineStyleProperty(CSSPropertyWidth,
-                                         m_fullscreenOrigWidth);
-          m_fullscreenOrigWidth = String();
-        }
-        if (!m_fullscreenOrigHeight.isNull()) {
-          canvas->setInlineStyleProperty(CSSPropertyWidth,
-                                         m_fullscreenOrigHeight);
-          m_fullscreenOrigHeight = String();
-        }
+        // TODO(klausw,crbug.com/698923): If compositor updates are
+        // suppressed, restore them here.
       } else {
         // TODO(junov, crbug.com/695497): Implement for OffscreenCanvas
       }
@@ -661,6 +668,8 @@ void VRDisplay::stopPresenting() {
 
   m_renderingContext = nullptr;
   m_contextGL = nullptr;
+  m_pendingSubmitFrame = false;
+  m_pendingPreviousFrameRender = false;
 }
 
 void VRDisplay::OnActivate(device::mojom::blink::VRDisplayEventReason reason) {
@@ -723,44 +732,6 @@ void VRDisplay::ConnectVSyncProvider() {
   }
 }
 
-void VRDisplay::onFullscreenCheck(TimerBase*) {
-  DCHECK(m_layer.source().isHTMLCanvasElement());
-  if (!m_isPresenting) {
-    m_fullscreenCheckTimer.stop();
-    return;
-  }
-  // TODO: This is a temporary measure to track if fullscreen mode has been
-  // exited by the UA. If so we need to end VR presentation. Soon we won't
-  // depend on the Fullscreen API to fake VR presentation, so this will
-  // become unnessecary. Until that point, though, this seems preferable to
-  // adding a bunch of notification plumbing to Fullscreen.
-  if (!Fullscreen::isCurrentFullScreenElement(
-          *m_layer.source().getAsHTMLCanvasElement())) {
-    // TODO(mthiesse): Due to asynchronous resizing, we might get kicked out of
-    // fullscreen when changing display parameters upon entering WebVR. So one
-    // time only, we reenter fullscreen after having left it; otherwise we exit
-    // presentation.
-    if (m_reenteredFullscreen) {
-      m_isPresenting = false;
-      OnPresentChange();
-      m_fullscreenCheckTimer.stop();
-      if (m_display)
-        m_display->ExitPresent();
-      return;
-    }
-    m_reenteredFullscreen = true;
-    auto canvas = m_layer.source().getAsHTMLCanvasElement();
-    Document* doc = this->document();
-    std::unique_ptr<UserGestureIndicator> gestureIndicator;
-    if (doc) {
-      gestureIndicator = WTF::wrapUnique(
-          new UserGestureIndicator(DocumentUserGestureToken::create(
-              doc, UserGestureToken::Status::PossiblyExistingGesture)));
-    }
-    Fullscreen::requestFullscreen(*canvas);
-  }
-}
-
 ScriptedAnimationController& VRDisplay::ensureScriptedAnimationController(
     Document* doc) {
   if (!m_scriptedAnimationController)