Web MIDI: add dynamic MidiManager instantiation support for Linux

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 5048829583dbd6588749d981f25420e9a65bc504..5f8feeac74fbb03606af2001b1e02cd4810f4104 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -96334,6 +96334,7 @@ value.
   <int value="-1869845022" label="force-show-update-menu-item"/>
   <int value="-1867382602" label="WebRTC-H264WithOpenH264FFmpeg:enabled"/>
   <int value="-1867342522" label="MaterialDesignHistory:enabled"/>
+  <int value="-1861814223" label="MidiManagerDynamicInstantiation:enabled"/>
   <int value="-1849706663" label="enable-password-force-saving:disabled"/>
   <int value="-1847835522" label="disable-touch-adjustment"/>
   <int value="-1847776781"
@@ -96975,6 +96976,7 @@ value.
   <int value="1062357243" label="remember-cert-error-decisions"/>
   <int value="1064288458" label="OfflineRecentPages:enabled"/>
   <int value="1067618884" label="enable-experimental-input-view-features"/>
+  <int value="1070164693" label="MidiManagerDynamicInstantiation:disabled"/>
   <int value="1070300488" label="disable-webgl"/>
   <int value="1081546525" label="ash-enable-docked-windows"/>
   <int value="1087235172" label="file-manager-enable-new-audio-player"/>