Add histogram definitions for Chrome OS boot mode.

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 eae5a18e985d0ff817e9c25b27a05d7446412a86..08d3844840307bbabbbeec61298ca6e11005aa72 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -43025,6 +43025,33 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Platform.BootMode.DevSwitch"
+    enum="Platform.BootMode.SwitchStatus">
+  <owner>mnissler@chromium.org</owner>
+  <summary>
+    Indicates the status of the developer switch on Chrome OS hardware. The
+    developer switch allows users to run their own code on the device.
+  </summary>
+</histogram>
+
+<histogram name="Platform.BootMode.FirmwareWriteProtect"
+    enum="Platform.BootMode.FirmwareWriteProtect">
+  <owner>mnissler@chromium.org</owner>
+  <summary>
+    On Chrome OS hardware, indicates whether flash write protection is enabled
+    for the firmware indicated by the histogram suffix.
+  </summary>
+</histogram>
+
+<histogram name="Platform.BootMode.WriteProtectSwitch"
+    enum="Platform.BootMode.SwitchStatus">
+  <owner>mnissler@chromium.org</owner>
+  <summary>
+    Indicates the status of the hardware write protect switch on Chrome OS
+    hardware. The write protect switch protects firmware from being rewritten.
+  </summary>
+</histogram>
+
 <histogram name="Platform.BootSectorsRead">
   <owner>sonnyrao@chromium.org</owner>
   <summary>
@@ -95202,6 +95229,19 @@ value.
   <int value="20" label="AUDIO_RENDERER_ERROR_SPLICE_FAILED"/>
 </enum>
 
+<enum name="Platform.BootMode.FirmwareWriteProtect" type="int">
+  <int value="0" label="Off"/>
+  <int value="1" label="On"/>
+  <int value="2" label="Zero length range"/>
+  <int value="3" label="Error"/>
+</enum>
+
+<enum name="Platform.BootMode.SwitchStatus" type="int">
+  <int value="0" label="Off"/>
+  <int value="1" label="On"/>
+  <int value="2" label="Error"/>
+</enum>
+
 <enum name="PlatformFileError" type="int">
   <int value="0" label="OK"/>
   <int value="1" label="FAILED"/>
@@ -109572,6 +109612,13 @@ value.
   <affected-histogram name="PhysicalWeb.State.Preference"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="Platform.FirmwareType" separator=".">
+  <suffix name="Main" label="Main processor firmware"/>
+  <suffix name="EC" label="Embedded Controller firmware"/>
+  <suffix name="PD" label="USB Power Delivery controller firmware"/>
+  <affected-histogram name="Platform.BootMode.FirmwareWriteProtect"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PlatformMeminfoPercentage" separator="">
   <suffix name="infoActive" label="Active memory."/>
   <suffix name="infoActiveAnon"