Implement EGL context priority if supported, use in VrShell

ui/gl/gl_context_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_context_egl.h"
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 24 matching lines @@
 #ifndef EGL_ANGLE_display_texture_share_group
 #define EGL_ANGLE_display_texture_share_group 1
 #define EGL_DISPLAY_TEXTURE_SHARE_GROUP_ANGLE 0x3AAF
 #endif /* EGL_ANGLE_display_texture_share_group */
 
 #ifndef EGL_ANGLE_create_context_client_arrays
 #define EGL_ANGLE_create_context_client_arrays 1
 #define EGL_CONTEXT_CLIENT_ARRAYS_ENABLED_ANGLE 0x3452
 #endif /* EGL_ANGLE_create_context_client_arrays */
 
+#ifndef EGL_CONTEXT_PRIORITY_LEVEL_IMG
+#define EGL_CONTEXT_PRIORITY_LEVEL_IMG 0x3100
+#define EGL_CONTEXT_PRIORITY_HIGH_IMG 0x3101
+#define EGL_CONTEXT_PRIORITY_MEDIUM_IMG 0x3102
+#define EGL_CONTEXT_PRIORITY_LOW_IMG 0x3103
+#endif /* EGL_CONTEXT_PRIORITY_LEVEL */
+
 using ui::GetLastEGLErrorString;
 
 namespace gl {
 
 GLContextEGL::GLContextEGL(GLShareGroup* share_group)
     : GLContextReal(share_group),
       context_(nullptr),
       display_(nullptr),
       config_(nullptr),
       unbind_fbo_on_makecurrent_(false) {}
@@ skipping 71 matching lines @@
   }
 
   if (GLSurfaceEGL::IsCreateContextWebGLCompatabilitySupported()) {
     context_attributes.push_back(EGL_CONTEXT_WEBGL_COMPATIBILITY_ANGLE);
     context_attributes.push_back(
         attribs.webgl_compatibility_context ? EGL_TRUE : EGL_FALSE);
   } else {
     DCHECK(!attribs.webgl_compatibility_context);
   }
 
+  if (GLSurfaceEGL::IsEGLContextPrioritySupported()) {
+    // Medium priority is the default, only set the attribute if
+    // a different priority is requested.
+    if (attribs.context_priority == ContextPriorityLow) {
+      DVLOG(1) << __FUNCTION__ << ": setting ContextPriorityLow";
+      context_attributes.push_back(EGL_CONTEXT_PRIORITY_LEVEL_IMG);
+      context_attributes.push_back(EGL_CONTEXT_PRIORITY_LOW_IMG);
+    } else if (attribs.context_priority == ContextPriorityHigh) {
+      DVLOG(1) << __FUNCTION__ << ": setting ContextPriorityHigh";
+      context_attributes.push_back(EGL_CONTEXT_PRIORITY_LEVEL_IMG);
+      context_attributes.push_back(EGL_CONTEXT_PRIORITY_HIGH_IMG);
+    }
+  }
+
   if (GLSurfaceEGL::HasEGLExtension("EGL_ANGLE_display_texture_share_group")) {
     context_attributes.push_back(EGL_DISPLAY_TEXTURE_SHARE_GROUP_ANGLE);
     context_attributes.push_back(
         attribs.global_texture_share_group ? EGL_TRUE : EGL_FALSE);
   } else {
     DCHECK(!attribs.global_texture_share_group);
   }
 
   if (GLSurfaceEGL::HasEGLExtension("EGL_ANGLE_create_context_client_arrays")) {
     // Disable client arrays if the context supports it
@@ skipping 135 matching lines @@
 
 bool GLContextEGL::WasAllocatedUsingRobustnessExtension() {
   return GLSurfaceEGL::IsCreateContextRobustnessSupported();
 }
 
 GLContextEGL::~GLContextEGL() {
   Destroy();
 }
 
 }  // namespace gl