Add GL_EXT_multisampled_render_to_texture support to command buffer.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 396311cffb1b6690d7c84ff0a2052ebc885206e1..b0fb12073b23ebf09122c4f9a48954e97aa950ec 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -100,6 +100,8 @@ void StringToWorkarounds(
 
 FeatureInfo::FeatureFlags::FeatureFlags()
     : chromium_framebuffer_multisample(false),
+      multisampled_render_to_texture(false),
+      use_img_for_multisampled_render_to_texture(false),
       oes_standard_derivatives(false),
       oes_egl_image_external(false),
       npot_ok(false),
@@ -453,20 +455,37 @@ void FeatureInfo::AddFeatures(const CommandLine& command_line) {
   }
 
   // Check for multisample support
-  bool ext_has_multisample =
-      extensions.Contains("GL_EXT_framebuffer_multisample");
-  if (!workarounds_.disable_angle_framebuffer_multisample) {
-    ext_has_multisample |=
-       extensions.Contains("GL_ANGLE_framebuffer_multisample");
-  }
-  if (!disallowed_features_.multisampling && ext_has_multisample) {
-    feature_flags_.chromium_framebuffer_multisample = true;
-    validators_.frame_buffer_target.AddValue(GL_READ_FRAMEBUFFER_EXT);
-    validators_.frame_buffer_target.AddValue(GL_DRAW_FRAMEBUFFER_EXT);
-    validators_.g_l_state.AddValue(GL_READ_FRAMEBUFFER_BINDING_EXT);
-    validators_.g_l_state.AddValue(GL_MAX_SAMPLES_EXT);
-    validators_.render_buffer_parameter.AddValue(GL_RENDERBUFFER_SAMPLES_EXT);
-    AddExtensionString("GL_CHROMIUM_framebuffer_multisample");
+  if (!disallowed_features_.multisampling) {
+    bool ext_has_multisample =
+        extensions.Contains("GL_EXT_framebuffer_multisample");
+    if (!workarounds_.disable_angle_framebuffer_multisample) {
+      ext_has_multisample |=
+         extensions.Contains("GL_ANGLE_framebuffer_multisample");
+    }
+    if (ext_has_multisample) {
+      feature_flags_.chromium_framebuffer_multisample = true;
+      validators_.frame_buffer_target.AddValue(GL_READ_FRAMEBUFFER_EXT);
+      validators_.frame_buffer_target.AddValue(GL_DRAW_FRAMEBUFFER_EXT);
+      validators_.g_l_state.AddValue(GL_READ_FRAMEBUFFER_BINDING_EXT);
+      validators_.g_l_state.AddValue(GL_MAX_SAMPLES_EXT);
+      validators_.render_buffer_parameter.AddValue(GL_RENDERBUFFER_SAMPLES_EXT);
+      AddExtensionString("GL_CHROMIUM_framebuffer_multisample");
+    } else {
+      if (extensions.Contains("GL_EXT_multisampled_render_to_texture")) {
+        feature_flags_.multisampled_render_to_texture = true;
+      } else if (extensions.Contains("GL_IMG_multisampled_render_to_texture")) {
+        feature_flags_.multisampled_render_to_texture = true;
+        feature_flags_.use_img_for_multisampled_render_to_texture = true;
+      }
+      if (feature_flags_.multisampled_render_to_texture) {
+        validators_.render_buffer_parameter.AddValue(
+            GL_RENDERBUFFER_SAMPLES_EXT);
+        validators_.g_l_state.AddValue(GL_MAX_SAMPLES_EXT);
+        validators_.frame_buffer_parameter.AddValue(
+            GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_SAMPLES_EXT);
+        AddExtensionString("GL_EXT_multisampled_render_to_texture");
+      }
+    }
   }
 
   if (extensions.Contains("GL_OES_depth24") || gfx::HasDesktopGLFeatures()) {