Add stats to distinguish android renderer crashes.

chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java
index 755c9dfaf8e21153328a57674df5c1d4459da00c..5c77580647fe8390bb504fc9c73663df0f32080e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabWebContentsObserver.java
@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.tab;
 
 import android.content.Context;
 import android.graphics.Color;
+import android.support.annotation.IntDef;
 import android.view.View;
 
 import org.chromium.base.ActivityState;
@@ -44,6 +45,20 @@ public class TabWebContentsObserver extends WebContentsObserver {
     private static final int TAB_RENDERER_CRASH_STATUS_HIDDEN_IN_BACKGROUND_APP = 2;
     private static final int TAB_RENDERER_CRASH_STATUS_MAX = 3;
 
+    // TabRendererExitStatus defined in tools/metrics/histograms/histograms.xml.
+    // Designed to replace TabRendererCrashStatus if numbers line up.
+    @IntDef({TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_FOREGROUND_APP,
+        TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_BACKGROUND_APP,
+        TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_FOREGROUND_APP,
+        TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_BACKGROUND_APP,
+        TAB_RENDERER_EXIT_STATUS_MAX})
+    private @interface TabRendererExitStatus {}
+    private static final int TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_FOREGROUND_APP = 0;
+    private static final int TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_BACKGROUND_APP = 1;
+    private static final int TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_FOREGROUND_APP = 2;
+    private static final int TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_BACKGROUND_APP = 3;
+    private static final int TAB_RENDERER_EXIT_STATUS_MAX = 4;
+
     private final Tab mTab;
     private int mThemeColor;
 
@@ -92,6 +107,25 @@ public class TabWebContentsObserver extends WebContentsObserver {
         RecordHistogram.recordEnumeratedHistogram(
                 "Tab.RendererCrashStatus", rendererCrashStatus, TAB_RENDERER_CRASH_STATUS_MAX);
 
+        // This will replace TabRendererCrashStatus if numbers line up.
+        boolean applicationInForeground = ApplicationStatus.hasVisibleActivities();

[no sievers, 2015/11/17 22:28:53]

There might be other reasons that our application would be marked as
'foreground', for example if you have a Service that calls startForeground()
such as MediaNotificationManager.java does for when there is media playing.

[Peter Wen, 2015/11/18 22:00:53]

Not sure how to best handle this situation where a service is in foreground but
rest of app is not. Would ApplicationStatus.determineApplicationState return
ApplicationState.HAS_RUNNING_ACTIVITIES? Or perhaps a service does not have a
corresponding ActivityInfo?

+        @TabRendererExitStatus int rendererExitStatus = TAB_RENDERER_EXIT_STATUS_MAX;
+        if (processWasOomProtected) {

[no sievers, 2015/11/17 22:28:53]

nit: Ok I see what you are trying to fix (I think), which is that our
'processWasOomProtected' is not accurate here. What this says is whether there
was a binding with BIND_IMPORTANT, but that only means 'foreground process level
when the *client is*' (the browser).
(http://developer.android.com/reference/android/content/Context.html#BIND_IMPO...)

So the way you have it now makes it slightly more confusing, since the notion of
'OOM protected' is still wrong.

And this is all just for dealing with the corner case of transitioning into the
background? Why is this in the order of seconds?
Can't we just make it so that we instantly remove the important bindings or so
when the application goes into the background and avoid the corner case?

[Yaron, 2015/11/18 15:25:17]

Hmm looks like the delay is 1-second and not 5 as I had thought
(BindingManagerImpl.DETACH_AS_ACTIVE_HIGH_END_DELAY_MILLIS).

But basically, the idea is to collect number of OOMs in spite of strong binding
where the child has strong binding and chrome is in fg

[Peter Wen, 2015/11/18 22:00:53]

Since BIND_IMPORTANT only works when the app is in the foreground, I've updated
the OOM protected condition to reflect that. WDYT?

+            if (applicationInForeground) {
+                rendererExitStatus = TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_FOREGROUND_APP;
+            } else {
+                rendererExitStatus = TAB_RENDERER_EXIT_STATUS_OOM_PROTECTED_IN_BACKGROUND_APP;
+            }
+        } else {
+            if (applicationInForeground) {
+                rendererExitStatus = TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_FOREGROUND_APP;
+            } else {
+                rendererExitStatus = TAB_RENDERER_EXIT_STATUS_NOT_PROTECTED_IN_BACKGROUND_APP;
+            }
+        }
+        RecordHistogram.recordEnumeratedHistogram(
+                "Tab.RendererExitStatus", rendererExitStatus, TAB_RENDERER_EXIT_STATUS_MAX);
+
         mTab.handleTabCrash();
 
         boolean sadTabShown = mTab.isShowingSadTab();