Enable creation of offscreen contexts which own their backing surface.

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 14 matching lines @@
 #ifndef EGL_CHROMIUM_create_context_bind_generates_resource
 #define EGL_CHROMIUM_create_context_bind_generates_resource 1
 #define EGL_CONTEXT_BIND_GENERATES_RESOURCE_CHROMIUM 0x3AAD
 #endif /* EGL_CHROMIUM_create_context_bind_generates_resource */
 
 #ifndef EGL_ANGLE_create_context_webgl_compatibility
 #define EGL_ANGLE_create_context_webgl_compatibility 1
 #define EGL_CONTEXT_WEBGL_COMPATIBILITY_ANGLE 0x3AAC
 #endif /* EGL_ANGLE_create_context_webgl_compatibility */
 
+#ifndef EGL_CONTEXT_PRIORITY_LEVEL_IMG
+#define EGL_CONTEXT_PRIORITY_LEVEL_IMG 0x3100
+#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 53 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() && attribs.low_priority) {
+    DVLOG(1) << __FUNCTION__ << ": setting low priority";
+    context_attributes.push_back(EGL_CONTEXT_PRIORITY_LEVEL_IMG);
+    context_attributes.push_back(EGL_CONTEXT_PRIORITY_LOW_IMG);
+  }
+
   // Append final EGL_NONE to signal the context attributes are finished
   context_attributes.push_back(EGL_NONE);
   context_attributes.push_back(EGL_NONE);
 
   context_ = eglCreateContext(
       display_, config_, share_group() ? share_group()->GetHandle() : nullptr,
       context_attributes.data());
 
   if (!context_) {
     LOG(ERROR) << "eglCreateContext failed with error "
@@ skipping 126 matching lines @@
 
 bool GLContextEGL::WasAllocatedUsingRobustnessExtension() {
   return GLSurfaceEGL::IsCreateContextRobustnessSupported();
 }
 
 GLContextEGL::~GLContextEGL() {
   Destroy();
 }
 
 }  // namespace gl