json: stop changing the content type on ipro'd json files

nginx side of the change: apache/incubator-pagespeed-ngx#1224

Fixes #1321

Author: jeffkaufman

install/mod_pagespeed_test/example.json

@@ -0,0 +1,4 @@
+{
+  "title": "example.json",
+  "contents": "an example of json"
+}

net/instaweb/rewriter/in_place_rewrite_context.cc

@@ -257,7 +257,7 @@ bool RecordingFetch::CanInPlaceRewrite() {
     return false;
   }
   if (type->type() == ContentType::kCss ||
-      type->IsJs() ||
+      type->IsJsLike() ||
       type->IsImage()) {
     RewriteDriver* driver = context_->Driver();
     HTTPCache* const cache = driver->server_context()->http_cache();
@@ -483,7 +483,7 @@ RewriteFilter* InPlaceRewriteContext::GetRewriteFilter(
       options->Enabled(RewriteOptions::kRewriteCss)) {
     return Driver()->FindFilter(RewriteOptions::kCssFilterId);
   }
-  if (type.IsJs() &&
+  if (type.IsJsLike() &&
       options->Enabled(RewriteOptions::kRewriteJavascriptExternal)) {
     return Driver()->FindFilter(RewriteOptions::kJavascriptMinId);
   }

net/instaweb/rewriter/javascript_filter.cc

@@ -312,8 +312,7 @@ class JavascriptFilter::Context : public SingleRewriteContext {
     // Try to preserve original content type to avoid breaking upstream proxies
     // and the like.
     const ContentType* content_type = script_resource->type();
-    if (content_type == nullptr ||
-        content_type->type() != ContentType::kJavascript) {
+    if (content_type == nullptr || !content_type->IsJsLike()) {
       content_type = &kContentTypeJavascript;
     }
     if (Driver()->Write(ResourceVector(1, script_resource),

net/instaweb/rewriter/rewrite_context.cc

@@ -3278,7 +3278,7 @@ bool RewriteContext::SendFallbackResponse(StringPiece output_url_base,
   const ContentType* content_type =
       async_fetch->response_headers()->DetermineContentType();
   if (content_type == NULL ||
-      !(content_type->IsJs() ||
+      !(content_type->IsJsLike() ||
         content_type->IsCss() ||
         content_type->IsImage() ||
         content_type == &kContentTypePdf)) {

pagespeed/kernel/http/content_type.cc

@@ -133,7 +133,7 @@ bool ContentType::IsCss() const {
   return type_ == kCss;
 }
 
-bool ContentType::IsJs() const {
+bool ContentType::IsJsLike() const {
   switch (type_) {
     case kJavascript:
     case kJson:
@@ -294,7 +294,7 @@ void MimeTypeListToContentTypeSet(
 
 bool ContentType::IsCompressible() const {
   // TODO(jcrowell): Investigate images with exif data as compressible.
-  return IsXmlLike() || IsHtmlLike() || IsJs() || IsCss() || type_ == kText;
+  return IsXmlLike() || IsHtmlLike() || IsJsLike() || IsCss() || type_ == kText;
 }
 
 bool ContentType::IsLikelyStaticResource() const {

pagespeed/kernel/http/content_type.h

@@ -67,8 +67,8 @@ struct ContentType {
   // Return true iff this content type is CSS.
   bool IsCss() const;
 
-  // Return true iff this content type is JS.
-  bool IsJs() const;
+  // Return true iff this content type is JS, or something similar like JSON.
+  bool IsJsLike() const;
 
   // Return true iff this content type is HTML, or XHTML, or some other such
   // thing (e.g. CE-HTML) that we can rewrite.

pagespeed/system/in_place_resource_recorder.cc

@@ -188,7 +188,7 @@ void InPlaceResourceRecorder::ConsiderResponseHeaders(
   if (content_type == NULL ||
       !(content_type->IsImage() ||
         content_type->IsCss() ||
-        content_type->IsJs())) {
+        content_type->IsJsLike())) {
     // We remember wrong mimetypes as uncacheable. This is slightly goofy,
     // and is inconsistent with how they are treated on normal rewrite path...
     DroppedAsUncacheable();

pagespeed/system/system_test.sh

@@ -366,6 +366,22 @@ echo $WGET_DUMP $TEST_ROOT/ipro/instant/deadline/purple.css
 OUT=$($WGET_DUMP $TEST_ROOT/ipro/instant/deadline/purple.css)
 check_from "$OUT" fgrep -q 'body{background:#9370db}'
 
+start_test json keeps its content type
+URL="$TEST_ROOT/example.json"
+OUT=$($WGET_DUMP "$URL?PageSpeed=off")
+# Verify that it's application/json without PageSpeed touching it.
+check_from "$OUT" grep '^Content-Type: application/json'
+OUT=$($WGET_DUMP "$URL")
+# Verify that it's application/json on the first PageSpeed load.
+check_from "$OUT" grep '^Content-Type: application/json'
+# Fetch it repeatedly until it's been IPRO-optimized.  This grep command is kind
+# of awkward, because fetch_until doesn't do quoting well.
+WGET_ARGS="--save-headers" fetch_until -save "$URL" \
+  "grep -c .title.:.example.json" 1
+OUT=$(cat $FETCH_UNTIL_OUTFILE)
+# Make sure we didn't change the content type to application/javascript.
+check_from "$OUT" grep '^Content-Type: application/json'
+
 start_test ShardDomain directive in per-directory config
 fetch_until -save $TEST_ROOT/shard/shard.html 'fgrep -c .pagespeed.ce' 4
 check [ $(grep -ce href=\"http://shard1 $FETCH_FILE) = 2 ];