gpu: Add a new extension CHROMIUM_deschedule.

components/mus/gles2/command_buffer_driver.cc

Index: components/mus/gles2/command_buffer_driver.cc
diff --git a/components/mus/gles2/command_buffer_driver.cc b/components/mus/gles2/command_buffer_driver.cc
index 798bb564f80bd52822834114aa8ed97f8b10647c..64244d8bfc893ce52f6129d13cfdb08ec947adbe 100644
--- a/components/mus/gles2/command_buffer_driver.cc
+++ b/components/mus/gles2/command_buffer_driver.cc
@@ -153,6 +153,10 @@ bool CommandBufferDriver::Initialize(
       &CommandBufferDriver::OnFenceSyncRelease, base::Unretained(this)));
   decoder_->SetWaitFenceSyncCallback(base::Bind(
       &CommandBufferDriver::OnWaitFenceSync, base::Unretained(this)));
+  decoder_->SetDescheduleUntilFinishedCallback(base::Bind(
+      &CommandBufferDriver::OnDescheduleUntilFinished, base::Unretained(this)));
+  decoder_->SetRescheduleAfterFinishedCallback(base::Bind(
+      &CommandBufferDriver::OnRescheduleAfterFinished, base::Unretained(this)));
 
   gpu::gles2::DisallowedFeatures disallowed_features;
 
@@ -516,6 +520,21 @@ bool CommandBufferDriver::OnWaitFenceSync(
   return executor_->scheduled();
 }
 
+void CommandBufferDriver::OnDescheduleUntilFinished() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(IsScheduled());
+  DCHECK(executor_->HasMoreIdleWork());
+
+  executor_->SetScheduled(false);
+}
+
+void CommandBufferDriver::OnRescheduleAfterFinished() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!executor_->scheduled());
+
+  executor_->SetScheduled(true);
+}
+
 void CommandBufferDriver::OnParseError() {
   DCHECK(CalledOnValidThread());
   gpu::CommandBuffer::State state = GetLastState();