Added UMA stat for tracking accidental navigations on double tap.

chrome/android/java/src/org/chromium/chrome/browser/TabBase.java

Index: chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
index 08c42218641dd5f81b5b74146a5db92564ea9d73..ba367ef7a9fd01a23a1f98f010e56ce4107b7278 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
@@ -221,7 +221,11 @@ public abstract class TabBase implements NavigationClient {
      * Goes to the navigation entry before the current one.
      */
     public void goBack() {
-        if (mContentViewCore != null) mContentViewCore.goBack();
+        if (mContentViewCore != null) {
+            mContentViewCore.reportActionForUMA(
+                ContentViewCore.UMAUserAction.NAVIGATE_BACK);
+            mContentViewCore.goBack();
+        }
     }
 
     /**
@@ -332,7 +336,11 @@ public abstract class TabBase implements NavigationClient {
 
     /** Stop the current navigation. */
     public void stopLoading() {
-        if (mContentViewCore != null) mContentViewCore.stopLoading();
+        if (mContentViewCore != null) {
+            mContentViewCore.reportActionForUMA(
+                ContentViewCore.UMAUserAction.NAVIGATE_STOP);
+            mContentViewCore.stopLoading();
+        }
     }
 
     /**