Add java-side support for _incremental instrumentation tests

build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java

Index: build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
diff --git a/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java b/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
index c1682e81e049ebda1ab784f4b628f5c96a803b75..c382799003489ba328a4b60fd7290c5218b53554 100644
--- a/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
+++ b/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
@@ -103,6 +103,10 @@ final class ClassLoaderPatcher {
      */
     void importNativeLibs(File libDir) throws ReflectiveOperationException, IOException {
         Log.i(TAG, "Importing native libraries from: " + libDir);
+        if (!libDir.exists()) {
+            Log.i(TAG, "No native libs exist.");
+            return;
+        }
         // The library copying is not necessary on older devices, but we do it anyways to
         // simplify things (it's fast compared to dexing).
         // https://code.google.com/p/android/issues/detail?id=79480
@@ -169,28 +173,34 @@ final class ClassLoaderPatcher {
 
     private static void copyChangedFiles(File srcDir, File dstDir) throws IOException {
         // No need to delete stale libs since libraries are loaded explicitly.
+        int numNotChanged = 0;
         for (File f : srcDir.listFiles()) {
             // Note: Tried using hardlinks, but resulted in EACCES exceptions.
             File dest = new File(dstDir, f.getName());
-            copyIfModified(f, dest);
+            if (!copyIfModified(f, dest)) {
+                numNotChanged++;
+            }
+        }
+        if (numNotChanged > 0) {
+            Log.i(TAG, numNotChanged + " libs already up-to-date.");
         }
     }
 
-    private static void copyIfModified(File src, File dest) throws IOException {
+    private static boolean copyIfModified(File src, File dest) throws IOException {
         long lastModified = src.lastModified();
-        if (!dest.exists() || dest.lastModified() != lastModified) {
-            Log.i(TAG, "Copying " + src + " -> " + dest);
-            FileInputStream istream = new FileInputStream(src);
-            FileOutputStream ostream = new FileOutputStream(dest);
-            ostream.getChannel().transferFrom(istream.getChannel(), 0, istream.getChannel().size());
-            istream.close();
-            ostream.close();
-            dest.setReadable(true, false);
-            dest.setExecutable(true,  false);
-            dest.setLastModified(lastModified);
-        } else {
-            Log.i(TAG, "Up-to-date: " + dest);
+        if (dest.exists() && dest.lastModified() == lastModified) {
+            return false;
         }
+        Log.i(TAG, "Copying " + src + " -> " + dest);
+        FileInputStream istream = new FileInputStream(src);
+        FileOutputStream ostream = new FileOutputStream(dest);
+        ostream.getChannel().transferFrom(istream.getChannel(), 0, istream.getChannel().size());
+        istream.close();
+        ostream.close();
+        dest.setReadable(true, false);
+        dest.setExecutable(true,  false);
+        dest.setLastModified(lastModified);
+        return true;
     }
 
     private void ensureAppFilesSubDirExists() {