Implement EGL context priority if supported, use in VrShell

ui/gl/gl_surface_egl.cc

 // Copyright (c) 2012 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 "ui/gl/gl_surface_egl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 110 matching lines @@
 EGLNativeDisplayType g_native_display = EGL_DEFAULT_DISPLAY;
 
 const char* g_egl_extensions = nullptr;
 bool g_egl_create_context_robustness_supported = false;
 bool g_egl_create_context_bind_generates_resource_supported = false;
 bool g_egl_create_context_webgl_compatability_supported = false;
 bool g_egl_sync_control_supported = false;
 bool g_egl_window_fixed_size_supported = false;
 bool g_egl_surfaceless_context_supported = false;
 bool g_egl_surface_orientation_supported = false;
+bool g_egl_context_priority_supported = false;
 bool g_use_direct_composition = false;
 
 class EGLSyncControlVSyncProvider : public SyncControlVSyncProvider {
  public:
   explicit EGLSyncControlVSyncProvider(EGLSurface surface)
       : SyncControlVSyncProvider(),
         surface_(surface) {
   }
 
   ~EGLSyncControlVSyncProvider() override {}
@@ skipping 377 matching lines @@
   g_egl_create_context_bind_generates_resource_supported =
       HasEGLExtension("EGL_CHROMIUM_create_context_bind_generates_resource");
   g_egl_create_context_webgl_compatability_supported =
       HasEGLExtension("EGL_ANGLE_create_context_webgl_compatibility");
   g_egl_sync_control_supported =
       HasEGLExtension("EGL_CHROMIUM_sync_control");
   g_egl_window_fixed_size_supported =
       HasEGLExtension("EGL_ANGLE_window_fixed_size");
   g_egl_surface_orientation_supported =
       HasEGLExtension("EGL_ANGLE_surface_orientation");
+  // According to https://source.android.com/compatibility/android-cdd.html the
+  // EGL_IMG_context_priority extension is mandatory for Virtual Reality High
+  // Performance support, but due to a bug in Android Nougat the extension
+  // isn't being reported even when it's present. As a fallback, check if other
+  // related extensions that were added for VR support are present, and assume
+  // that this implies context priority is also supported. See also:
+  // https://github.com/googlevr/gvr-android-sdk/issues/330
+  g_egl_context_priority_supported =
+      HasEGLExtension("EGL_IMG_context_priority") ||
+      (HasEGLExtension("EGL_ANDROID_front_buffer_auto_refresh") &&
+       HasEGLExtension("EGL_ANDROID_create_native_client_buffer"));
 
   // Need EGL_ANGLE_flexible_surface_compatibility to allow surfaces with and
   // without alpha to be bound to the same context.
   g_use_direct_composition =
       HasEGLExtension("EGL_ANGLE_direct_composition") &&
       HasEGLExtension("EGL_ANGLE_flexible_surface_compatibility") &&
       !base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableDirectComposition);
 
   // TODO(oetuaho@nvidia.com): Surfaceless is disabled on Android as a temporary
@@ skipping 82 matching lines @@
 bool GLSurfaceEGL::IsCreateContextWebGLCompatabilitySupported() {
   return g_egl_create_context_webgl_compatability_supported;
 }
 
 // static
 bool GLSurfaceEGL::IsEGLSurfacelessContextSupported() {
   return g_egl_surfaceless_context_supported;
 }
 
 // static
+bool GLSurfaceEGL::IsEGLContextPrioritySupported() {
+  return g_egl_context_priority_supported;
+}
+
+// static
 bool GLSurfaceEGL::IsDirectCompositionSupported() {
   return g_use_direct_composition;
 }
 
 GLSurfaceEGL::~GLSurfaceEGL() {}
 
 // InitializeDisplay is necessary because the static binding code
 // needs a full Display init before it can query the Display extensions.
 // static
 EGLDisplay GLSurfaceEGL::InitializeDisplay(
@@ skipping 548 matching lines @@
 }
 
 void* SurfacelessEGL::GetShareHandle() {
   return NULL;
 }
 
 SurfacelessEGL::~SurfacelessEGL() {
 }
 
 }  // namespace gl