Add a switch for tablet power button behavior

ash/common/ash_switches.cc

Index: ash/common/ash_switches.cc
diff --git a/ash/common/ash_switches.cc b/ash/common/ash_switches.cc
index b8b3578df90199317a32f586464a5012998ea408..af4a1b531005a52c89a0e45ff03b95dae22a1602 100644
--- a/ash/common/ash_switches.cc
+++ b/ash/common/ash_switches.cc
@@ -61,6 +61,10 @@ const char kAshEnablePalette[] = "ash-enable-palette";
 const char kAshEnablePaletteOnAllDisplays[] =
     "ash-enable-palette-on-all-displays";
 
+// Enables tablet power button behavior for convertible/tablet devices.
+// TODO(warx): Enable or remove this switch once crbug.com/633304 is fully
+// finished.
+const char kAshEnableTabletPowerButton[] = "enable-tablet-power-button";

[Daniel Erat, 2016/11/15 15:10:42]

this should probably be ash-enable-tablet-power-button to match most other ash
switches, right? (i don't know why enable-touchview doesn't have the same
prefix.)

[Qiang(Joe) Xu, 2016/11/15 17:29:09]

yes.. changed.
I didn't change enable-touchview in this CL (it needs to match the chromeos
platform code).

 #endif
 
 // Enables the observation of accelerometer events to enter touch-view mode.