Added UMA stat for tracking accidental navigations on double tap.

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index c423adb26a525acca2f5cb89f0401acbcca22de2..b487f7e3ea9d37cf22e8db03aa2c015e458fdc41 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -11,6 +11,7 @@
 #include "base/command_line.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "cc/layers/layer.h"
@@ -1620,6 +1621,32 @@ void ContentViewCoreImpl::SetAccessibilityEnabled(JNIEnv* env, jobject obj,
   }
 }
 
+void ContentViewCoreImpl::SendDelayedTapUma(
+    JNIEnv* env,
+    jobject obj) {
+   content::RecordAction(content::UserMetricsAction("DelayedGestureTap"));

[Rick Byers, 2013/11/01 14:45:09]

This is OK (I think it gives us the main measure we want), but I was actually
thinking we'd use a histogram with two values - delayed or not delayed.  That
way we can also chart what fraction of taps are delayed over time (as a result
of all our efforts to delay fewer taps).  Sorry I wasn't clear about that.  What
do you think - worth changing?

[bokan, 2013/11/01 18:52:44]

Yup, makes sense and shouldn't be hard.

+}
+
+void ContentViewCoreImpl::SendActionAfterDoubleTapUma(
+    JNIEnv* env,
+    jobject obj,
+    int type,
+    bool hasDelay,
+    int count) {
+  // This UMA stat tracks a user's action after a double tap within
+  // k seconds (where k == 5 currently). This UMA will tell us if
+  // removing the tap gesture delay will lead to significantly more
+  // accidental navigations after a double tap.
+  if(hasDelay) {
+      UMA_HISTOGRAM_ENUMERATION("UserInput.ActionAfterDoubleTapWithDelay",
+        type, count);
+  } else {
+      UMA_HISTOGRAM_ENUMERATION("UserInput.ActionAfterDoubleTapNoDelay",
+        type, count);
+  }
+
+}
+
 void ContentViewCoreImpl::SendOrientationChangeEventInternal() {
   RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
   if (rwhv)