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 3de48e1fb7388ea4fe0a227c7523a59bae1dcff3..8336da94101e6fe0afce7a26d700ccbfdb1a684b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -7397,10 +7397,31 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Crashpad.CrashReportSize" units="bytes">
-  <owner>scottmg@chromium.org</owner>
+  <owner>crashpad-dev@chromium.org</owner>
   <summary>The size of a crash report minidump on disk when captured.</summary>
 </histogram>
 
+<histogram name="Crashpad.ExceptionCaptureResult"
+    enum="CrashpadExceptionCaptureResult">
+  <owner>crashpad-dev@chromium.org</owner>
+  <summary>The outcome of execution of the Crashpad exception handler.</summary>
+</histogram>
+
+<histogram name="Crashpad.ExceptionCode.Mac">

[Alexei Svitkine (slow), 2016/09/20 18:58:55]

Please make an enum for this too, even if you don't fully fill it in. Having
enum= set makes our dashboard treat it as an enum - as opposed to numeric - so
it won't try to do percentiles and other useless stuff.

[scottmg, 2016/09/20 21:33:09]

Done. Just added a few that I could find easily that seemed plausibly useful.

+  <owner>crashpad-dev@chromium.org</owner>
+  <summary>The exception code encountered in a crash on Mac OS X.</summary>
+</histogram>
+
+<histogram name="Crashpad.ExceptionCode.Win" enum="CrashExitCodes">
+  <owner>crashpad-dev@chromium.org</owner>
+  <summary>The exception code encountered in a crash on Windows.</summary>
+</histogram>
+
+<histogram name="Crashpad.ExceptionEncountered">
+  <owner>crashpad-dev@chromium.org</owner>
+  <summary>A count of the number of exceptions handled by Crashpad.</summary>

[Alexei Svitkine (slow), 2016/09/20 18:58:55]

This is not logging a count - it's logging a boolean sample every time an
exception is handled instead. Please re-word to make that clear and associate
this with a enum="BooleanHit".

However, as a meta question, we don't generally encourage these kinds of metrics
- because numbers in isolation are not meaningful unless you compare to
something.

For example, is 198 a lot? Very few? Hard to say unless you have some other
information such as number of launches, number of users, or some other
denominator.

[scottmg, 2016/09/20 21:33:09]

The idea was that this is a count we can compare against the count of
ExceptionCaptureResult (which tracks all the exits from the function). This one
is here so that it's set right away as early as possible, and then we can infer
if Crashpad is crashing by a difference in these counts.

[Alexei Svitkine (slow), 2016/09/21 15:47:17]

I see. Comparing the difference of the two results seems like it would be
tedious to do. So I suggest actually adding another bucket to this histogram
(i.e. making an enum with two enums) that's logged when ExceptionCaptureResult
is logged - so that you can clearly do the comparison you want within the same
histogram.

(If you do that, make a helper function that logs that histogram and call it
from both places - so you don't repeat the macro for the same histogram since
the macros does expand to a bunch of code.)

+</histogram>
+
 <histogram name="CrashReport.BreakpadCrashDumpOutcome" enum="DumpOutcome">
   <obsolete>
     Deprecated as of 04/2016 as CrashPad does not implement this.
@@ -74568,6 +74589,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2147483646" label="STATUS_DATATYPE_MISALIGNMENT"/>
 </enum>
 
+<enum name="CrashpadExceptionCaptureResult" type="int">
+  <int value="0" label="kSuccess"/>
+  <int value="1" label="kUnexpectedExceptionBehavior"/>
+  <int value="2" label="kFailedDueToSuspendSelf"/>
+  <int value="3" label="kSnapshotFailed"/>
+  <int value="4" label="kExceptionInitializationFailed"/>
+  <int value="5" label="kPrepareNewCrashReportFailed"/>
+  <int value="6" label="kMinidumpWriteFailed"/>
+  <int value="7" label="kFinishWritingCrashReportFailed"/>
+</enum>
+
 <enum name="CreatePersistentHistogramResult" type="int">
   <int value="0" label="Success: Histogram created in persistent space."/>
   <int value="1" label="Error: Invalid metadata pointer. (coding error)"/>