Upstream MemoryUma and use it for all activities.

This achieves a couple of goals:
1) Upstreams MemoryUma
2) Pulls it up from ChromeTabbedActivity (internal) to
AsyncInitializationActivity. This ensures that other activities (e.g.
DocumentActivity) also report memory warnings.
3) Instantiate MemoryUma!! This was broken in
https://chrome-internal-review.googlesource.com/161577 so low-memory
warnings haven't been reported since M35! :(

BUG=428903

Review URL: https://codereview.chromium.org/961323003

Cr-Commit-Position: refs/heads/master@{#318696}

chrome/android/java/src/org/chromium/chrome/browser/init/AsyncInitializationActivity.java

@@ -15,6 +15,8 @@ import android.view.View;
 import android.view.ViewTreeObserver;
 import android.view.ViewTreeObserver.OnPreDrawListener;
 
+import org.chromium.chrome.browser.metrics.MemoryUma;
+
 /**
  * An activity that talks with application and activity level delegates for async initialization.
  */
@@ -30,6 +32,7 @@ public abstract class AsyncInitializationActivity extends ActionBarActivity impl
     private Bundle mSavedInstanceState;
     private boolean mDestroyed;
     private NativeInitializationController mNativeInitializationController;
+    private MemoryUma mMemoryUma;
 
     public AsyncInitializationActivity() {
         mHandler = new Handler();
@@ -71,6 +74,7 @@ public abstract class AsyncInitializationActivity extends ActionBarActivity impl
 
     @Override
     public void finishNativeInitialization() {
+        mMemoryUma = new MemoryUma();
         mNativeInitializationController.onNativeInitializationComplete();
     }
 
@@ -146,6 +150,7 @@ public abstract class AsyncInitializationActivity extends ActionBarActivity impl
     @Override
     public void onStop() {
         super.onStop();
+        if (mMemoryUma != null) mMemoryUma.onStop();
         mNativeInitializationController.onStop();
     }
 
@@ -196,6 +201,19 @@ public abstract class AsyncInitializationActivity extends ActionBarActivity impl
         return false;
     }
 
+    @Override
+    public void onLowMemory() {
+        super.onLowMemory();
+        if (mMemoryUma != null) mMemoryUma.onLowMemory();
+    }
+
+    @Override
+    public void onTrimMemory(int level) {
+        super.onTrimMemory(level);
+        if (mMemoryUma != null) mMemoryUma.onTrimMemory(level);
+    }
+
+
     /**
      * Extending classes should implement this and call {@link Activity#setContentView(int)} in it.
      */

chrome/android/java/src/org/chromium/chrome/browser/metrics/MemoryUma.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.metrics;
+
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_BACKGROUND;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_COMPLETE;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_MODERATE;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_MODERATE;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN;
+
+import android.os.Build;
+import android.os.SystemClock;
+
+import org.chromium.base.metrics.RecordHistogram;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Centralizes UMA data collection for Android-specific memory conditions.
+ */
+public class MemoryUma {
+    // AndroidMemoryNotificationBackground defined in tools/metrics/histograms/histograms.xml.
+    private static final int BACKGROUND_TRIM_UI_HIDDEN = 0;
+    private static final int BACKGROUND_TRIM_BACKGROUND = 1;
+    private static final int BACKGROUND_TRIM_MODERATE = 2;
+    private static final int BACKGROUND_TRIM_COMPLETE = 3;
+    private static final int BACKGROUND_MAX = 4;
+
+    // AndroidMemoryNotificationForeground defined in tools/metrics/histograms/histograms.xml.
+    private static final int FOREGROUND_TRIM_MODERATE = 0;
+    private static final int FOREGROUND_TRIM_LOW = 1;
+    private static final int FOREGROUND_TRIM_CRITICAL = 2;
+    private static final int FOREGROUND_LOW = 3;
+    private static final int FOREGROUND_MAX = 4;
+
+    // Timestamp of the last time we received a LowMemory call since Chrome is in foreground.
+    private long mLastLowMemoryMsec = -1;
+
+    public void onStop() {
+        mLastLowMemoryMsec = -1;
+    }
+
+    public void onLowMemory() {
+        memoryNotificationForeground(FOREGROUND_LOW);
+        long now = SystemClock.elapsedRealtime();
+        if (mLastLowMemoryMsec >= 0) {
+            RecordHistogram.recordCustomTimesHistogram("MemoryAndroid.LowMemoryTimeBetween",
+                    now - mLastLowMemoryMsec, 0, TimeUnit.MINUTES.toMillis(10),
+                    TimeUnit.MILLISECONDS, 50);
+        }
+        mLastLowMemoryMsec = now;
+    }
+
+    public void onTrimMemory(int level) {
+        if (level >= TRIM_MEMORY_COMPLETE) {
+            memoryNotificationBackground(BACKGROUND_TRIM_COMPLETE);
+        } else if (level >= TRIM_MEMORY_MODERATE) {
+            memoryNotificationBackground(BACKGROUND_TRIM_MODERATE);
+        } else if (level >= TRIM_MEMORY_BACKGROUND) {
+            memoryNotificationBackground(BACKGROUND_TRIM_BACKGROUND);
+        } else if (level >= TRIM_MEMORY_UI_HIDDEN) {
+            memoryNotificationBackground(BACKGROUND_TRIM_UI_HIDDEN);
+        } else if (level >= TRIM_MEMORY_RUNNING_CRITICAL) {
+            memoryNotificationForeground(FOREGROUND_TRIM_CRITICAL);
+        } else if (level >= TRIM_MEMORY_RUNNING_LOW) {
+            memoryNotificationForeground(FOREGROUND_TRIM_LOW);
+        } else if (level >= TRIM_MEMORY_RUNNING_MODERATE) {
+            memoryNotificationForeground(FOREGROUND_TRIM_MODERATE);
+        }
+    }
+
+    private static void memoryNotificationForeground(int notification) {
+        assert notification >= 0 && notification < FOREGROUND_MAX;
+        // Before Jelly Bean we have only LowMemory foreground notification.
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) return;
+        RecordHistogram.recordEnumeratedHistogram("MemoryAndroid.NotificationForeground",
+                notification, FOREGROUND_MAX);
+    }
+
+    private static void memoryNotificationBackground(int notification) {
+        assert notification >= 0 && notification < BACKGROUND_MAX;
+        RecordHistogram.recordEnumeratedHistogram("MemoryAndroid.NotificationBackground",
+                notification, BACKGROUND_MAX);
+    }
+}