[ON HOLD] Implement pull-based design for content decoding

net/url_request/url_request_http_job.cc

Index: net/url_request/url_request_http_job.cc
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index d2a4797bff6a8310d6aede6477d1cf2198a2a28b..11c09420fc70358b8a61dcc7e112ad0d8449c049 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -32,6 +32,11 @@
 #include "net/base/url_util.h"
 #include "net/cert/cert_status_flags.h"
 #include "net/cookies/cookie_store.h"
+#include "net/filter/brotli_source_stream.h"
+#include "net/filter/filter_source_stream.h"
+#include "net/filter/gzip_source_stream.h"
+#include "net/filter/sdch_source_stream.h"
+#include "net/filter/source_stream.h"
 #include "net/http/http_content_disposition.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_request_headers.h"
@@ -62,6 +67,12 @@ static const char kAvailDictionaryHeader[] = "Avail-Dictionary";
 
 namespace {
 
+const char kDeflate[] = "deflate";
+const char kGZip[] = "gzip";
+const char kSdch[] = "sdch";
+const char kXGZip[] = "x-gzip";
+const char kBrotli[] = "br";
+
 // True if the request method is "safe" (per section 4.2.1 of RFC 7231).
 bool IsMethodSafe(const std::string& method) {
   return method == "GET" || method == "HEAD" || method == "OPTIONS" ||
@@ -178,85 +189,67 @@ net::URLRequestRedirectJob* MaybeInternallyRedirect(
 
 namespace net {
 
-class URLRequestHttpJob::HttpFilterContext : public FilterContext {
+class URLRequestHttpJob::SdchContext : public SdchPolicyDelegate::Context {
  public:
-  explicit HttpFilterContext(URLRequestHttpJob* job);
-  ~HttpFilterContext() override;
-
-  // FilterContext implementation.
+  explicit SdchContext(URLRequestHttpJob* job);
+  ~SdchContext() override;
+  // SdchPolicyDelegate::Context implementation
   bool GetMimeType(std::string* mime_type) const override;
-  bool GetURL(GURL* gurl) const override;
-  base::Time GetRequestTime() const override;
+  bool GetURL(GURL* url) const override;
+  // base::Time GetRequestTime() const override;
   bool IsCachedContent() const override;
+  SdchManager* GetSdchManager() const override;
   SdchManager::DictionarySet* SdchDictionariesAdvertised() const override;
-  int64_t GetByteReadCount() const override;
+  // int64_t GetByteReadCount() const override;
   int GetResponseCode() const override;
-  const URLRequestContext* GetURLRequestContext() const override;
-  void RecordPacketStats(StatisticSelector statistic) const override;
   const BoundNetLog& GetNetLog() const override;
 
  private:
+  // URLRequestHttpJob owns SdchPolicyDelegate which owns the context, so it
+  // is okay to have a raw pointer reference to |job_|.
   URLRequestHttpJob* job_;
 
-  // URLRequestHttpJob may be detached from URLRequest, but we still need to
+  // URLRequestHttpJob may be detached from URLRequest, but still need to
   // return something.
   BoundNetLog dummy_log_;
 
-  DISALLOW_COPY_AND_ASSIGN(HttpFilterContext);
+  DISALLOW_COPY_AND_ASSIGN(SdchContext);
 };
 
-URLRequestHttpJob::HttpFilterContext::HttpFilterContext(URLRequestHttpJob* job)
-    : job_(job) {
-  DCHECK(job_);
-}
+URLRequestHttpJob::SdchContext::SdchContext(URLRequestHttpJob* job)
+    : job_(job) {}
 
-URLRequestHttpJob::HttpFilterContext::~HttpFilterContext() {
-}
+URLRequestHttpJob::SdchContext::~SdchContext() {}
 
-bool URLRequestHttpJob::HttpFilterContext::GetMimeType(
-    std::string* mime_type) const {
+bool URLRequestHttpJob::SdchContext::GetMimeType(std::string* mime_type) const {
   return job_->GetMimeType(mime_type);
 }
 
-bool URLRequestHttpJob::HttpFilterContext::GetURL(GURL* gurl) const {
+bool URLRequestHttpJob::SdchContext::GetURL(GURL* gurl) const {
   if (!job_->request())
     return false;
   *gurl = job_->request()->url();
   return true;
 }
 
-base::Time URLRequestHttpJob::HttpFilterContext::GetRequestTime() const {
-  return job_->request() ? job_->request()->request_time() : base::Time();
+bool URLRequestHttpJob::SdchContext::IsCachedContent() const {
+  return job_->is_cached_content_;
 }
 
-bool URLRequestHttpJob::HttpFilterContext::IsCachedContent() const {
-  return job_->is_cached_content_;
+SdchManager* URLRequestHttpJob::SdchContext::GetSdchManager() const {
+  return job_->request() ? job_->request()->context()->sdch_manager() : nullptr;
 }
 
 SdchManager::DictionarySet*
-URLRequestHttpJob::HttpFilterContext::SdchDictionariesAdvertised() const {
+URLRequestHttpJob::SdchContext::SdchDictionariesAdvertised() const {
   return job_->dictionaries_advertised_.get();
 }
 
-int64_t URLRequestHttpJob::HttpFilterContext::GetByteReadCount() const {
-  return job_->prefilter_bytes_read();
-}
-
-int URLRequestHttpJob::HttpFilterContext::GetResponseCode() const {
+int URLRequestHttpJob::SdchContext::GetResponseCode() const {
   return job_->GetResponseCode();
 }
 
-const URLRequestContext*
-URLRequestHttpJob::HttpFilterContext::GetURLRequestContext() const {
-  return job_->request() ? job_->request()->context() : NULL;
-}
-
-void URLRequestHttpJob::HttpFilterContext::RecordPacketStats(
-    StatisticSelector statistic) const {
-  job_->RecordPacketStats(statistic);
-}
-
-const BoundNetLog& URLRequestHttpJob::HttpFilterContext::GetNetLog() const {
+const BoundNetLog& URLRequestHttpJob::SdchContext::GetNetLog() const {
   return job_->request() ? job_->request()->net_log() : dummy_log_;
 }
 
@@ -309,7 +302,6 @@ URLRequestHttpJob::URLRequestHttpJob(
       bytes_observed_in_packets_(0),
       request_time_snapshot_(),
       final_packet_time_(),
-      filter_context_(new HttpFilterContext(this)),
       on_headers_received_callback_(
           base::Bind(&URLRequestHttpJob::OnHeadersReceivedCallback,
                      base::Unretained(this))),
@@ -331,14 +323,10 @@ URLRequestHttpJob::~URLRequestHttpJob() {
   DCHECK(!sdch_test_control_ || !sdch_test_activated_);
   if (!is_cached_content_) {
     if (sdch_test_control_)
-      RecordPacketStats(FilterContext::SDCH_EXPERIMENT_HOLDBACK);
+      RecordPacketStats(SdchPolicyDelegate::Context::SDCH_EXPERIMENT_HOLDBACK);
     if (sdch_test_activated_)
-      RecordPacketStats(FilterContext::SDCH_EXPERIMENT_DECODE);
+      RecordPacketStats(SdchPolicyDelegate::Context::SDCH_EXPERIMENT_DECODE);
   }
-  // Make sure SDCH filters are told to emit histogram data while
-  // filter_context_ is still alive.
-  DestroyFilters();
-
   DoneWithRequest(ABORTED);
 }
 
@@ -1158,27 +1146,79 @@ void URLRequestHttpJob::PopulateNetErrorDetails(
   return transaction_->PopulateNetErrorDetails(details);
 }
 
-std::unique_ptr<Filter> URLRequestHttpJob::SetupFilter() const {
+std::unique_ptr<SourceStream> URLRequestHttpJob::SetUpSourceStream() {
   DCHECK(transaction_.get());
   if (!response_info_)
     return nullptr;
 
-  std::vector<Filter::FilterType> encoding_types;
-  std::string encoding_type;
   HttpResponseHeaders* headers = GetResponseHeaders();
+  std::string type;
+  std::vector<SourceStream::SourceType> types;
   size_t iter = 0;
-  while (headers->EnumerateHeader(&iter, "Content-Encoding", &encoding_type)) {
-    encoding_types.push_back(Filter::ConvertEncodingToType(encoding_type));
+  while (headers->EnumerateHeader(&iter, "Content-Encoding", &type)) {
+    if (base::LowerCaseEqualsASCII(type, kBrotli)) {
+      types.push_back(SourceStream::TYPE_BROTLI);
+    } else if (base::LowerCaseEqualsASCII(type, kDeflate)) {
+      types.push_back(SourceStream::TYPE_DEFLATE);
+    } else if (base::LowerCaseEqualsASCII(type, kGZip) ||
+               base::LowerCaseEqualsASCII(type, kXGZip)) {
+      types.push_back(SourceStream::TYPE_GZIP);
+    } else if (base::LowerCaseEqualsASCII(type, kSdch)) {
+      types.push_back(SourceStream::TYPE_SDCH);
+    }
   }
 
-  // Even if encoding types are empty, there is a chance that we need to add
-  // some decoding, as some proxies strip encoding completely. In such cases,
-  // we may need to add (for example) SDCH filtering (when the context suggests
-  // it is appropriate).
-  Filter::FixupEncodingTypes(*filter_context_, &encoding_types);
+  // SDCH-specific hack: if the first filter is SDCH, add a gzip filter in front
+  // of it in fallback mode.
+  // Some proxies (found currently in Argentina) strip the Content-Encoding
+  // text from "sdch,gzip" to a mere "sdch" without modifying the compressed
+  // payload.  To handle this gracefully, we simulate the "probably" deleted
+  // ",gzip" by appending a tentative gzip decode, which will default to a
+  // no-op pass through filter if it doesn't get gzip headers where expected.
+  if (types.size() == 1 && types.at(0) == SourceStream::TYPE_SDCH) {
+    types.insert(types.begin(), SourceStream::TYPE_GZIP_FALLBACK);
+    // TODO(xunjieli): Add UMA to see how common this is.
+  }
 
-  return !encoding_types.empty()
-      ? Filter::Factory(encoding_types, *filter_context_) : NULL;
+  std::unique_ptr<SourceStream> upstream = URLRequestJob::SetUpSourceStream();
+  for (std::vector<SourceStream::SourceType>::reverse_iterator r_iter =
+           types.rbegin();
+       r_iter != types.rend(); ++r_iter) {
+    std::unique_ptr<FilterSourceStream> downstream;
+    SourceStream::SourceType type = *r_iter;
+    switch (type) {
+      case SourceStream::TYPE_BROTLI:
+        downstream = CreateBrotliSourceStream(std::move(upstream));
+        break;
+      case SourceStream::TYPE_SDCH: {
+        std::unique_ptr<SdchContext> context(new SdchContext(this));
+        sdch_delegate_.reset(new SdchPolicyDelegate(std::move(context)));
+        downstream.reset(
+            new SdchSourceStream(std::move(upstream), sdch_delegate_.get()));
+        break;
+      }
+      case SourceStream::TYPE_GZIP:
+        downstream = GzipSourceStream::Create(
+            std::move(upstream), GzipSourceStream::GZIP_SOURCE_STREAM_GZIP);
+        break;
+      case SourceStream::TYPE_DEFLATE:
+        downstream = GzipSourceStream::Create(
+            std::move(upstream), GzipSourceStream::GZIP_SOURCE_STREAM_DEFLATE);
+        break;
+      case SourceStream::TYPE_GZIP_FALLBACK:
+        downstream = GzipSourceStream::Create(
+            std::move(upstream),
+            GzipSourceStream::GZIP_SOURCE_STREAM_GZIP_WITH_FALLBACK);
+        break;
+      default:
+        NOTREACHED();
+        return nullptr;
+    }
+    if (downstream == nullptr)
+      return nullptr;
+    upstream = std::move(downstream);
+  }
+  return upstream;
 }
 
 bool URLRequestHttpJob::CopyFragmentOnRedirect(const GURL& location) const {
@@ -1477,35 +1517,34 @@ void URLRequestHttpJob::UpdatePacketReadTimes() {
 }
 
 void URLRequestHttpJob::RecordPacketStats(
-    FilterContext::StatisticSelector statistic) const {
+    SdchPolicyDelegate::Context::StatisticSelector statistic) const {
   if (!packet_timing_enabled_ || (final_packet_time_ == base::Time()))
     return;
 
   base::TimeDelta duration = final_packet_time_ - request_time_snapshot_;
   switch (statistic) {
-    case FilterContext::SDCH_DECODE: {
+    case SdchPolicyDelegate::Context::StatisticSelector::SDCH_DECODE: {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Sdch3.Network_Decode_Bytes_Processed_b",
-          static_cast<int>(bytes_observed_in_packets_), 500, 100000, 100);
+                                  static_cast<int>(bytes_observed_in_packets_),
+                                  500, 100000, 100);
       return;
     }
-    case FilterContext::SDCH_PASSTHROUGH: {
+    case SdchPolicyDelegate::Context::StatisticSelector::SDCH_PASSTHROUGH: {
       // Despite advertising a dictionary, we handled non-sdch compressed
       // content.
       return;
     }
 
-    case FilterContext::SDCH_EXPERIMENT_DECODE: {
-      UMA_HISTOGRAM_CUSTOM_TIMES("Sdch3.Experiment3_Decode",
-                                  duration,
-                                  base::TimeDelta::FromMilliseconds(20),
-                                  base::TimeDelta::FromMinutes(10), 100);
+    case SdchPolicyDelegate::Context::SDCH_EXPERIMENT_DECODE: {
+      UMA_HISTOGRAM_CUSTOM_TIMES("Sdch3.Experiment3_Decode", duration,
+                                 base::TimeDelta::FromMilliseconds(20),
+                                 base::TimeDelta::FromMinutes(10), 100);
       return;
     }
-    case FilterContext::SDCH_EXPERIMENT_HOLDBACK: {
-      UMA_HISTOGRAM_CUSTOM_TIMES("Sdch3.Experiment3_Holdback",
-                                  duration,
-                                  base::TimeDelta::FromMilliseconds(20),
-                                  base::TimeDelta::FromMinutes(10), 100);
+    case SdchPolicyDelegate::Context::SDCH_EXPERIMENT_HOLDBACK: {
+      UMA_HISTOGRAM_CUSTOM_TIMES("Sdch3.Experiment3_Holdback", duration,
+                                 base::TimeDelta::FromMilliseconds(20),
+                                 base::TimeDelta::FromMinutes(10), 100);
       return;
     }
     default: