Show "storage almost full" message when a page is saved offline

chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java
index 26ff8c85bc4bcfe6bd594e73d8a20f418d1ad741..5e62bead7af8c3f6661bb030053807ed5988b7af 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offline_pages/OfflinePageBridge.java
@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.offline_pages;
 
+import android.os.Environment;
+
 import org.chromium.base.ObserverList;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
@@ -23,6 +25,8 @@ import java.util.List;
 @JNINamespace("offline_pages::android")
 public final class OfflinePageBridge {
 
+    private static final long STORAGE_ALMOST_FULL_THRESHOLD_BYTES = 10L * (1 << 20);  // 10M
+
     private long mNativeOfflinePageBridge;
     private boolean mIsNativeOfflinePageModelLoaded;
     private final ObserverList<OfflinePageModelObserver> mObservers =
@@ -94,6 +98,15 @@ public final class OfflinePageBridge {
     }
 
     /**
+     * Returns true if the stoarge is almost full which indicates that the user probably needs to
+     * free up some space.
+     */
+    public static boolean isStorageAlmostFull() {
+        return Environment.getExternalStorageDirectory().getUsableSpace()

[newt (away), 2015/08/21 01:13:37]

Is the "external storage directory" the same place where we store offline pages?
I would have expected they'd be stored in /data/data/com.android.chrome/ along
with our other app data.

[fgorski, 2015/08/21 17:55:25]

We actually store it in the downloads folder, so that the archive files are
available to other applications.

[newt (away), 2015/08/21 18:56:37]

Gotcha. In that case, this looks good to me.

+                < STORAGE_ALMOST_FULL_THRESHOLD_BYTES;
+    }
+
+    /**
      * Destroys native offline pages bridge. It should be called during
      * destruction to ensure proper cleanup.
      */