Implement EGL context priority if supported, use in VrShell

chrome/browser/android/vr_shell/vr_shell_gl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/android/vr_shell/vr_shell_gl.h"
 
 #include <chrono>
 #include <limits>
 #include <utility>
 
@@ skipping 259 matching lines @@
     surface_ = gl::init::CreateViewGLSurface(window);
   } else {
     CHECK(surfaceless_rendering_);
     surface_ = gl::init::CreateOffscreenGLSurface(gfx::Size());
   }
   if (!surface_.get()) {
     LOG(ERROR) << "gl::init::CreateOffscreenGLSurface failed";
     ForceExitVr();
     return;
   }
-  context_ = gl::init::CreateGLContext(nullptr, surface_.get(),
-                                       gl::GLContextAttribs());
+
+  gl::GLContextAttribs attribs;
+  attribs.context_priority = gl::ContextPriorityHigh;
+  context_ = gl::init::CreateGLContext(nullptr, surface_.get(), attribs);
   if (!context_.get()) {
     LOG(ERROR) << "gl::init::CreateGLContext failed";
     ForceExitVr();
     return;
   }
   if (!context_->MakeCurrent(surface_.get())) {
     LOG(ERROR) << "gl::GLContext::MakeCurrent() failed";
     ForceExitVr();
     return;
   }
@@ skipping 1247 matching lines @@
   // This assumes that the initial webvr_surface_size_ was set to the
   // appropriate recommended render resolution as the default size during
   // InitializeGl. Revisit if the initialization order changes.
   device::mojom::VRDisplayInfoPtr info =
       device::GvrDelegate::CreateVRDisplayInfo(gvr_api_.get(),
                                                webvr_surface_size_, device_id);
   browser_->RunVRDisplayInfoCallback(callback, &info);
 }
 
 }  // namespace vr_shell