Allow to have different files for different ISAs in NaCl manifest.

ppapi/native_client/src/trusted/plugin/json_manifest.cc

Index: ppapi/native_client/src/trusted/plugin/json_manifest.cc
===================================================================
--- ppapi/native_client/src/trusted/plugin/json_manifest.cc	(revision 193364)
+++ ppapi/native_client/src/trusted/plugin/json_manifest.cc	(working copy)
@@ -252,17 +252,19 @@
     }
   }
 
-  // TODO(elijahtaylor) add ISA resolver here if we expand ISAs to include
-  // micro-architectures that can resolve to multiple valid sandboxes.
-  bool has_isa = dictionary.isMember(sandbox_isa);
-  bool has_portable = dictionary.isMember(kPortableKey);
+  if (!sandbox_isa.empty()) {

[Mark Seaborn, 2013/04/18 01:17:46]

Why not remove this whole block?

AFAICS, this block would only apply to two cases:

 * The "program" section.  But the NaCl app will fail to start anyway if there's
no program specified for the current arch!

 * The "interpreter" section.  But this section is unused, AFAIK.  We should
probably remove the code that looks for it.

[halyavin, 2013/04/18 07:33:27]

Once we remove the whole block, absence of URL will be treated as an empty URL. 
Empty relative URL is valid, so we may have some weird error messages instead. 
There is probably a better way to implement this part of manifest parsing but I
don't want to make major changes now.

+    // TODO(elijahtaylor) add ISA resolver here if we expand ISAs to include
+    // micro-architectures that can resolve to multiple valid sandboxes.
+    bool has_isa = dictionary.isMember(sandbox_isa);
+    bool has_portable = dictionary.isMember(kPortableKey);
 
-  if (!has_isa && !has_portable) {
-    error_info->SetReport(
-        ERROR_MANIFEST_PROGRAM_MISSING_ARCH,
-        nacl::string("manifest: no version of ") + parent_key +
-        " given for current arch and no portable version found.");
-    return false;
+    if (!has_isa && !has_portable) {
+      error_info->SetReport(
+          ERROR_MANIFEST_PROGRAM_MISSING_ARCH,
+          nacl::string("manifest: no version of ") + parent_key +
+          " given for current arch and no portable version found.");
+      return false;
+    }
   }
 
   return true;
@@ -298,8 +300,12 @@
   if (url == NULL || pnacl_options == NULL || error_info == NULL)
     return false;
 
-  if (!IsValidISADictionary(dictionary, parent_key, sandbox_isa, error_info))
+  if (!IsValidISADictionary(dictionary, parent_key, sandbox_isa, error_info)) {
+    error_info->SetReport(ERROR_MANIFEST_RESOLVE_URL,
+                          "architecture " + sandbox_isa +
+                          " is not found for file " + parent_key);
     return false;
+  }
 
   *url = "";
 
@@ -434,7 +440,7 @@
       nacl::string file_name = members[i];
       if (!IsValidISADictionary(files[file_name],
                                 file_name,
-                                sandbox_isa_,
+                                nacl::string(),
                                 error_info)) {
         return false;
       }