gpu: Implement GL_INTEL_framebuffer_CMAA via shaders in the GPU Service

ui/gl/gl_switches.cc

Index: ui/gl/gl_switches.cc
diff --git a/ui/gl/gl_switches.cc b/ui/gl/gl_switches.cc
index 31030c4e8e4f6434e3213a26db6aad0afe424c65..23fc099c8d55bc0bdff8852f30841ffb79eb9e85 100644
--- a/ui/gl/gl_switches.cc
+++ b/ui/gl/gl_switches.cc
@@ -93,6 +93,11 @@ const char kOverrideUseGLWithOSMesaForTests[] =
 // Disables specified comma separated GL Extensions if found.
 const char kDisableGLExtensions[] = "disable-gl-extensions";
 
+// Enables GL_INTEL_framebuffer_CMAA via shaders. Will be used if the platform
+// does not support GL_INTEL_framebuffer_CMAA and the context is at least
+// OpenGL ES 3.1 or OpenGL 3.0 with the required extensions.
+const char kEnableCMAAShaders[] = "enable-cmaa-shaders";
+
 // This is the list of switches passed from this file that are passed from the
 // GpuProcessHost to the GPU Process. Add your switch to this list if you need
 // to read it in the GPU process, else don't add it.
@@ -107,6 +112,7 @@ const char* kGLSwitchesCopiedFromGpuProcessHost[] = {
     kOverrideUseGLWithOSMesaForTests,
     kUseANGLE,
     kDisableDirectComposition,
+    kEnableCMAAShaders,
 };
 const int kGLSwitchesCopiedFromGpuProcessHostNumSwitches =
     arraysize(kGLSwitchesCopiedFromGpuProcessHost);