WebVR: implement SetSurfaceHandleCHROMIUM extension for gvr_device.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index e9d8b80cc9189fba180c977637e133fcb0250e3f..e4dda2d44d30bc75380860dbd2ec25774ddf4a81 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -46,6 +46,7 @@
 #include "core/layout/LayoutBox.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "core/origin_trials/OriginTrials.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "modules/webgl/ANGLEInstancedArrays.h"
 #include "modules/webgl/EXTBlendMinMax.h"
@@ -621,6 +622,15 @@ WebGLRenderingContextBase::createContextProviderInternal(
 
   Platform::ContextAttributes contextAttributes =
       toPlatformContextAttributes(attributes, webGLVersion);
+
+  // If there's a possibility this context may be used with WebVR make sure it
+  // is created with an offscreen surface that can be swapped out for a
+  // VR-specific surface if needed.
+  if (RuntimeEnabledFeatures::webVREnabled() ||
+      OriginTrials::webVREnabled(scriptState->getExecutionContext())) {
+    contextAttributes.supportOwnOffscreenSurface = true;
+  }
+
   Platform::GraphicsInfo glInfo;
   std::unique_ptr<WebGraphicsContext3DProvider> contextProvider;
   const auto& url = canvas ? canvas->document().topDocument().url()