Add enable flag for pointer events in about://flags

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index b7d4010e1c5d394affd89e15c222e0779c070c22..123976e0af428058e45ed0ad54ace8ff0c7f8637 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -321,6 +321,9 @@ const char kEnableCredentialManagerAPI[]    = "enable-credential-manager-api";
 const char kEnablePreferCompositingToLCDText[] =
     "enable-prefer-compositing-to-lcd-text";
 
+// Enable partial experimental support for pointer event feature in blink
+const char kEnablePointerEvents[]           = "enable-pointer-events";
+
 // Disable one or more Blink runtime-enabled features.
 // Use names from RuntimeEnabledFeatures.in, separated by commas.
 // Applied before kDisableBlinkFeatures, and after other flags that change these