Measure the usage of navigator.vibrate in for user gesture & subframe.

third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp

Index: third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp
diff --git a/third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp b/third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp
index ae5ca2c5c3622862bdb791b90a39b4e520bbbc8e..c33c8c4875774a643f12a3624ca4e5788409c0e3 100644
--- a/third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp
+++ b/third_party/WebKit/Source/modules/vibration/NavigatorVibration.cpp
@@ -24,6 +24,8 @@
 #include "core/frame/UseCounter.h"

[Michael van Ouwerkerk, 2016/06/28 11:45:52]

Delete this as it is no longer used.

 #include "core/page/Page.h"
 #include "modules/vibration/VibrationController.h"
+#include "platform/Histogram.h"
+#include "platform/UserGestureIndicator.h"
 
 namespace blink {
 
@@ -71,9 +73,20 @@ bool NavigatorVibration::vibrate(Navigator& navigator, const VibrationPattern& p
     if (!frame)
         return false;
 
-    UseCounter::count(frame, UseCounter::NavigatorVibrate);
-    if (!frame->isMainFrame())
-        UseCounter::count(frame, UseCounter::NavigatorVibrateSubFrame);
+    const unsigned userGestureBit = 0x1;

[Michael van Ouwerkerk, 2016/06/28 11:45:53]

I don't find this section very readable, using bit manipulation. Why not have
some conditionals that set the actual enum value directly? You could get rid of
the static_cast as well that way.

+    const unsigned subFrameBit = 0x2;
+    const unsigned crossOriginFrameBit = 0x4;
+    unsigned vibrateParams = 0;
+    if (UserGestureIndicator::processingUserGesture())
+        vibrateParams |= userGestureBit;
+    if (!frame->isMainFrame()) {
+        if (frame->isCrossOrigin())
+            vibrateParams |= crossOriginFrameBit;
+        else
+            vibrateParams |= subFrameBit;
+    }
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, NavigatorVibrateHistogram, ("Vibration.Context", NavigatorVibrationType::EnumMax));
+    NavigatorVibrateHistogram.count(static_cast<NavigatorVibrationType>(vibrateParams));
 
     DCHECK(frame->document());
     DCHECK(frame->page());