cast: Provide an API to enable/disable the display

This will be used to turn off the display when the device is in idle
state. Turning off the display has significant power savings.

BUG=b/156411764
TEST=Manually verified that disabling the displays turns off the LCD.

Change-Id: I70e9c0cf9db473e143c92a88b888de9a73b8bff2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2273478Reviewed-by: Albert Chaulk <achaulk@chromium.org>
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#785943}

chromecast/browser/cast_display_configurator.cc

@@ -127,6 +127,28 @@ void CastDisplayConfigurator::OnConfigurationChanged() {
       false /* force_initial_configure */));
 }
 
+void CastDisplayConfigurator::EnableDisplay() {
+  if (!delegate_ || !display_)
+    return;
+
+  display::DisplayConfigurationParams display_config_params(
+      display_->display_id(), gfx::Point(), display_->native_mode());
+  delegate_->Configure(display_config_params, base::BindOnce([](bool status) {
+                         LOG_IF(FATAL, !status) << "Failed to enable display";
+                       }));
+}
+
+void CastDisplayConfigurator::DisableDisplay() {
+  if (!delegate_ || !display_)
+    return;
+
+  display::DisplayConfigurationParams display_config_params(
+      display_->display_id(), gfx::Point(), nullptr);
+  delegate_->Configure(display_config_params, base::BindOnce([](bool status) {
+                         LOG_IF(ERROR, !status) << "Failed to disable display";
+                       }));
+}
+
 void CastDisplayConfigurator::ConfigureDisplayFromCommandLine() {
   const gfx::Size size = GetScreenResolution();
   UpdateScreen(kStubDisplayId, gfx::Rect(size), GetDeviceScaleFactor(size),

chromecast/browser/cast_display_configurator.h

@@ -45,6 +45,9 @@ class CastDisplayConfigurator : public display::NativeDisplayObserver {
   void OnConfigurationChanged() override;
   void OnDisplaySnapshotsInvalidated() override {}
 
+  void EnableDisplay();
+  void DisableDisplay();
+
   void ConfigureDisplayFromCommandLine();
   void SetColorMatrix(const std::vector<float>& color_matrix);
   void SetGammaCorrection(