Revert of Enable creation of offscreen contexts which own their backing surface.

ui/gl/gl_context_egl.cc

Index: ui/gl/gl_context_egl.cc
diff --git a/ui/gl/gl_context_egl.cc b/ui/gl/gl_context_egl.cc
index 6e85155f8347be950b51b2829b134f4308013990..1cd08cd40496efa08ee512b4dfe85efcc9d69296 100644
--- a/ui/gl/gl_context_egl.cc
+++ b/ui/gl/gl_context_egl.cc
@@ -32,12 +32,6 @@
 #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 {
@@ -111,12 +105,6 @@
     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);