Add UMA for testing whether the Chromium library was page aligned in the APK file.

base/android/java/src/org/chromium/base/library_loader/LibraryLoader.java

 // Copyright 2014 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.base.library_loader;
 
 import android.content.Context;
 import android.os.SystemClock;
 import android.util.Log;
 
@@ skipping 296 matching lines @@
         nativeRecordNativeLibraryHack(sNativeLibraryHackWasUsed);
     }
 
     // Record Chromium linker histogram state for the main browser process. Called from
     // onNativeInitializationComplete().
     private static void recordBrowserProcessHistogram(Context context) {
         if (Linker.isUsed()) {
             nativeRecordChromiumAndroidLinkerBrowserHistogram(sIsUsingBrowserSharedRelros,
                                                               sLoadAtFixedAddressFailed,
                                                               getLibraryLoadFromApkStatus(context));
+            if (Linker.isInZipFile()) {
+                nativeRecordChromiumAndroidLinkerLibraryAlignmentInApk(

[picksi1, 2014/10/28 11:37:08]

This reads like you're checking if the linker is in a zip file (?) if this is
your function should it be called isAPKZipped() ... or have I misunderstood its
use?

[petrcermak, 2014/10/28 12:16:48]

I don't like the name either. It returns true iff the Chromium library should be
loaded directly from the APK. I didn't change the name because the whole class
will need a complete refactoring anyway.

+                        getLibraryAlignmentInApk(context));
+            }
         }
     }
 
     // Returns the device's status for loading a library directly from the APK file.
     // This method can only be called when the Chromium linker is used.
     private static int getLibraryLoadFromApkStatus(Context context) {
         assert Linker.isUsed();
 
         if (sLibraryWasLoadedFromApk) {
             return LibraryLoadFromApkStatusCodes.SUCCESSFUL;
         }
 
         if (context == null) {
             Log.w(TAG, "Unknown APK filename due to null context");
             return LibraryLoadFromApkStatusCodes.UNKNOWN;
         }
 
         return Linker.checkLibraryLoadFromApkSupport(context.getApplicationInfo().sourceDir) ?
                 LibraryLoadFromApkStatusCodes.SUPPORTED :
                 LibraryLoadFromApkStatusCodes.NOT_SUPPORTED;
     }
 
+    // Returns true if the Chromium library is page aligned in the APK file.
+    // This method can only be called when the Chromium linker is used and the library
+    // can be loaded directly from the APK file.
+    private static boolean getLibraryAlignmentInApk(Context context) {
+        assert Linker.isUsed();
+        assert Linker.isInZipFile();
+
+        if (NativeLibraries.LIBRARIES.length != 2) {
+            Log.w(TAG, "NativeLibraryes.LIBRARIES should contain exactly 2 libraries");

[picksi1, 2014/10/28 11:37:08]

Is there a const or enum etc. we can use to avoid using a magic number 2 here?

[petrcermak, 2014/10/28 12:16:48]

I removed this code. The point was that there should be only the Chromium linker
library (which is *not* loaded directly from the APK) and Chromium library
(which *is* loaded directly from the APK).

+        }
+
+        for (String library : NativeLibraries.LIBRARIES) {
+            if (!Linker.isLinkerLibrary(library)) {
+                return Linker.checkLibraryAlignedInApk(context.getApplicationInfo().sourceDir,
+                                                       System.mapLibraryName(library));
+            }
+        }
+
+        return false;
+    }
+
     // Register pending Chromium linker histogram state for renderer processes. This cannot be
     // recorded as a histogram immediately because histograms and IPC are not ready at the
     // time it are captured. This function stores a pending value, so that a later call to
     // RecordChromiumAndroidLinkerRendererHistogram() will record it correctly.
     public static void registerRendererProcessHistogram(boolean requestedSharedRelro,
                                                         boolean loadAtFixedAddressFailed) {
         if (Linker.isUsed()) {
             nativeRegisterChromiumAndroidLinkerRendererHistogram(requestedSharedRelro,
                                                                  loadAtFixedAddressFailed);
         }
@@ skipping 11 matching lines @@
 
     // Method called to record statistics about the Chromium linker operation for the main
     // browser process. Indicates whether the linker attempted relro sharing for the browser,
     // and if it did, whether the library failed to load at a fixed address. Also records
     // support for loading a library directly from the APK file.
     private static native void nativeRecordChromiumAndroidLinkerBrowserHistogram(
             boolean isUsingBrowserSharedRelros,
             boolean loadAtFixedAddressFailed,
             int libraryLoadFromApkStatus);
 
+    // Method called to record statistics about the page alignment of the Chromium library
+    // in the APK file.
+    private static native void nativeRecordChromiumAndroidLinkerLibraryAlignmentInApk(
+            boolean aligned);
+
     // Method called to register (for later recording) statistics about the Chromium linker
     // operation for a renderer process. Indicates whether the linker attempted relro sharing,
     // and if it did, whether the library failed to load at a fixed address.
     private static native void nativeRegisterChromiumAndroidLinkerRendererHistogram(
             boolean requestedSharedRelro,
             boolean loadAtFixedAddressFailed);
 
     // Get the version of the native library. This is needed so that we can check we
     // have the right version before initializing the (rest of the) JNI.
     private static native String nativeGetVersionNumber();
 
     private static native void nativeRecordNativeLibraryHack(boolean usedHack);
 }