touch: Add a new metric.

BUG=162511

Review URL: https://codereview.chromium.org/11416188

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170086 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 36 insertions, 1 deletions

diff --git a/ash/touch/touch_uma.cc b/ash/touch/touch_uma.cc
index d8117b6..7ddfa19 100644
--- a/ash/touch/touch_uma.cc
+++ b/ash/touch/touch_uma.cc
@@ -7,6 +7,7 @@
 #include "ash/shell_delegate.h"
 #include "base/metrics/histogram.h"
 #include "base/stringprintf.h"
+#include "ui/aura/env.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_property.h"
@@ -247,7 +248,9 @@ UMAEventType UMAEventTypeFromEvent(const ui::Event& event) {
 namespace ash {
 namespace internal {
 
-TouchUMA::TouchUMA() {
+TouchUMA::TouchUMA()
+    : touch_in_progress_(false),
+      burst_length_(0) {
 }
 
 TouchUMA::~TouchUMA() {
@@ -284,6 +287,8 @@ void TouchUMA::RecordTouchEvent(aura::Window* target,
       static_cast<int>(std::max(event.radius_x(), event.radius_y())),
       1, 500, 100);
 
+  UpdateBurstData(event);
+
   WindowTouchDetails* details = target->GetProperty(kWindowTouchDetails);
   if (!details) {
     details = new WindowTouchDetails;
@@ -388,5 +393,27 @@ void TouchUMA::RecordTouchEvent(aura::Window* target,
   }
 }
 
+void TouchUMA::UpdateBurstData(const ui::TouchEvent& event) {
+  if (event.type() == ui::ET_TOUCH_PRESSED) {
+    if (!touch_in_progress_) {
+      base::TimeDelta difference = event.time_stamp() - last_touch_down_time_;
+      if (difference > base::TimeDelta::FromMilliseconds(250)) {
+        if (burst_length_) {
+          UMA_HISTOGRAM_COUNTS_100("Ash.TouchStartBurst",
+                                   std::min(burst_length_, 100));
+        }
+        burst_length_ = 1;
+      } else {
+        ++burst_length_;
+      }
+    }
+    touch_in_progress_ = true;
+    last_touch_down_time_ = event.time_stamp();
+  } else if (event.type() == ui::ET_TOUCH_RELEASED) {
+    if (!aura::Env::GetInstance()->is_touch_down())
+      touch_in_progress_ = false;
+  }
+}
+
 }  // namespace internal
 }  // namespace ash
diff --git a/ash/touch/touch_uma.h b/ash/touch/touch_uma.h
index cab7edc..46805b1 100644
--- a/ash/touch/touch_uma.h
+++ b/ash/touch/touch_uma.h
@@ -31,6 +31,14 @@ class TouchUMA {
                         const ui::TouchEvent& event);
 
  private:
+  void UpdateBurstData(const ui::TouchEvent& event);
+
+  // These are used to measure the number of touch-start events we receive in a
+  // quick succession, regardless of the target window.
+  bool touch_in_progress_;
+  int burst_length_;
+  base::TimeDelta last_touch_down_time_;
+
   DISALLOW_COPY_AND_ASSIGN(TouchUMA);
 };