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..cd79259632a92c8d1aa447cec4da8dd85ef63e54 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
@@ -169,14 +173,20 @@ 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 {

[nyquist, 2016/02/10 07:08:32]

Optional nit: Add a super-tiny comment as to what the return value means?

[agrieve, 2016/02/10 16:47:15]

Electing not to since it's private and is clear from the code.

         long lastModified = src.lastModified();
         if (!dest.exists() || dest.lastModified() != lastModified) {

[nyquist, 2016/02/10 07:08:32]

Optional nit: Would it be easier to read with something like:
if (dest.exists() && dest.lastModified() == lastModified) return false;
?

[agrieve, 2016/02/10 16:47:15]

Done.

             Log.i(TAG, "Copying " + src + " -> " + dest);
@@ -188,9 +198,9 @@ final class ClassLoaderPatcher {
             dest.setReadable(true, false);
             dest.setExecutable(true,  false);
             dest.setLastModified(lastModified);
-        } else {
-            Log.i(TAG, "Up-to-date: " + dest);
+            return true;
         }
+        return false;
     }
 
     private void ensureAppFilesSubDirExists() {