cc: Invalidate framebuffer contents when clearing

content/common/gpu/client/context_provider_command_buffer.cc

Index: content/common/gpu/client/context_provider_command_buffer.cc
diff --git a/content/common/gpu/client/context_provider_command_buffer.cc b/content/common/gpu/client/context_provider_command_buffer.cc
index 2c5b4da55fc9cfb091e068ed760b147c013ffc2a..87be5a021465055791fa67cb16cd2dab9a4da29e 100644
--- a/content/common/gpu/client/context_provider_command_buffer.cc
+++ b/content/common/gpu/client/context_provider_command_buffer.cc
@@ -264,6 +264,9 @@ void ContextProviderCommandBuffer::InitializeCapabilities() {
   caps.texture_usage = extension_set.count("GL_ANGLE_texture_usage") > 0;
   caps.texture_storage = extension_set.count("GL_EXT_texture_storage") > 0;
 
+  caps.discard_framebuffer =
+      extension_set.count("GL_EXT_discard_framebuffer") > 0;
+
   capabilities_ = caps;
 }