Fix potential GPU crash caused by VT switching

ui/display/chromeos/display_configurator.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/display/chromeos/display_configurator.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 539 matching lines @@
       base::Bind(&DisplayConfigurator::OnDisplayControlTaken,
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void DisplayConfigurator::OnDisplayControlTaken(
     const DisplayControlCallback& callback,
     bool success) {
   display_control_changing_ = false;
   display_externally_controlled_ = !success;
   if (success) {
+    // Force a configuration since the display configuration may have changed.
     force_configure_ = true;
-    RunPendingConfiguration();
+    // Restore the last power state used before releasing control.
+    SetDisplayPower(requested_power_state_, kSetDisplayPowerNoFlags,
+                    base::Bind(&DoNothing));
   }
 
   callback.Run(success);
 }
 
 void DisplayConfigurator::RelinquishControl(
     const DisplayControlCallback& callback) {
   if (display_control_changing_) {
     callback.Run(false);
     return;
   }
 
   if (display_externally_controlled_) {
     callback.Run(true);
     return;
   }
 
   // For simplicity, just fail if in the middle of a display configuration.
   if (configuration_task_) {
     callback.Run(false);
     return;
   }
 
-  // Set the flag early such that an incoming configuration event won't start
-  // while we're releasing control of the displays.
   display_control_changing_ = true;
-  display_externally_controlled_ = true;
-  native_display_delegate_->RelinquishDisplayControl(
-      base::Bind(&DisplayConfigurator::OnDisplayControlRelinquished,
+
+  // Turn off the displays before releasing control since we're no longer using
+  // them for output.
+  SetDisplayPowerInternal(
+      chromeos::DISPLAY_POWER_ALL_OFF, kSetDisplayPowerNoFlags,
+      base::Bind(&DisplayConfigurator::SendRelinquishDisplayControl,
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
+void DisplayConfigurator::SendRelinquishDisplayControl(
+    const DisplayControlCallback& callback, bool success) {
+  if (success) {
+    // Set the flag early such that an incoming configuration event won't start
+    // while we're releasing control of the displays.
+    display_externally_controlled_ = true;
+    native_display_delegate_->RelinquishDisplayControl(
+        base::Bind(&DisplayConfigurator::OnDisplayControlRelinquished,
+                   weak_ptr_factory_.GetWeakPtr(), callback));
+  } else {
+    display_control_changing_ = false;
+    callback.Run(false);
+  }
+}
+
 void DisplayConfigurator::OnDisplayControlRelinquished(
     const DisplayControlCallback& callback,
     bool success) {
   display_control_changing_ = false;
   display_externally_controlled_ = success;
   if (!success) {
     force_configure_ = true;
     RunPendingConfiguration();
   }
 
@@ skipping 567 matching lines @@
   last_virtual_display_id_ = max_display_id & 0xff;
 
   return true;
 }
 
 bool DisplayConfigurator::IsDisplayOn() const {
   return current_power_state_ != chromeos::DISPLAY_POWER_ALL_OFF;
 }
 
 }  // namespace ui