Monochrome: Unroll loops in onResourcesLoaded()

In (crrev.com/952097), a runtime check was added to Resource arrays such
that only resource ids that start with "0x7f" ie. application resources
(vs "0x01" which are system resources) are to have their package id
transformed. This lead to startup performance degradation.

This CL changes this check to a compile time check and unrolls the
arrays at compile time (when packaging resources and creating the R.java
file we have all the resource ids already).

Bug: 821425
Change-Id: Id977901d7ecaf24df76806ce9c39a38f40a57061
Reviewed-on: https://chromium-review.googlesource.com/974079
Commit-Queue: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545102}

build/android/gyp/process_resources.py

@@ -308,7 +308,7 @@ def _FixPackageIds(resource_value):
   # changes to the correct package id at runtime.
   # resource_value is a string with either, a single value '0x12345678', or an
   # array of values like '{ 0xfedcba98, 0x01234567, 0x56789abc }'
-  return re.sub(r'0x(?!01)\d\d', r'0x7f', resource_value)
+  return re.sub(r'0x(?!01)[0-9a-f]{2}', r'0x7f', resource_value)
 
 
 def _CreateRJavaFile(package, resources_by_type, shared_resources,
@@ -336,6 +336,16 @@ def _CreateRJavaFile(package, resources_by_type, shared_resources,
   else:
     final_resources_by_type = resources_by_type
 
+  def _UnrollArray(entry):
+    res_ids = re.findall(r'0x[0-9a-f]{8}', entry.value)
+    qualified_array_name = '%s.%s' % (entry.resource_type, entry.name)
+    unrolled = []
+    for i, res_id in enumerate(res_ids):
+      if res_id.startswith('0x7f'):
+        unrolled.append("%s[%d] ^= packageIdTransform;" %
+                        (qualified_array_name, i))
+    return unrolled
+
   # Keep these assignments all on one line to make diffing against regular
   # aapt-generated files easier.
   create_id = ('{{ e.resource_type }}.{{ e.name }} ^= packageIdTransform;')
@@ -360,13 +370,6 @@ public final class R {
     }
     {% endfor %}
     {% if shared_resources %}
-    public static void transfromArray(int[] array, int packageIdTransform) {
-        for (int i=0; i < array.length; i++) {
-            if ((array[i] >>> 24) == 0x7f) {
-                array[i] ^= packageIdTransform;
-            }
-        }
-    }
     public static void onResourcesLoaded(int packageId) {
         assert !sResourcesDidLoad;
         sResourcesDidLoad = true;
@@ -375,7 +378,9 @@ public final class R {
         onResourcesLoaded{{ resource_type|title }}(packageIdTransform);
         {% for e in non_final_resources[resource_type] %}
         {% if e.java_type == 'int[]' %}
-        transfromArray({{ e.resource_type }}.{{ e.name }}, packageIdTransform);
+        {% for line in unrollArray(e) %}
+        {{ line }}
+        {% endfor %}
         {% endif %}
         {% endfor %}
         {% endfor %}
@@ -398,7 +403,8 @@ public final class R {
                          resource_types=sorted(resources_by_type),
                          shared_resources=shared_resources,
                          final_resources=final_resources_by_type,
-                         non_final_resources=non_final_resources_by_type)
+                         non_final_resources=non_final_resources_by_type,
+                         unrollArray=_UnrollArray)
 
 
 def _GenerateGlobs(pattern):