diff --git a/http2/adapter/callback_visitor.h b/http2/adapter/callback_visitor.h
index 38c8dda..8a32862 100644
--- a/http2/adapter/callback_visitor.h
+++ b/http2/adapter/callback_visitor.h
@@ -8,13 +8,14 @@
 #include "http2/adapter/http2_visitor_interface.h"
 #include "http2/adapter/nghttp2_util.h"
 #include "third_party/nghttp2/src/lib/includes/nghttp2/nghttp2.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
 // This visitor implementation accepts a set of nghttp2 callbacks and a "user
 // data" pointer, and invokes the callbacks according to HTTP/2 events received.
-class CallbackVisitor : public Http2VisitorInterface {
+class QUICHE_EXPORT_PRIVATE CallbackVisitor : public Http2VisitorInterface {
  public:
   explicit CallbackVisitor(Perspective perspective,
                            const nghttp2_session_callbacks& callbacks,
@@ -76,7 +77,7 @@
   void OnErrorDebug(absl::string_view message) override;
 
  private:
-  struct StreamInfo {
+  QUICHE_EXPORT_PRIVATE struct StreamInfo {
     bool before_sent_headers = false;
     bool sent_headers = false;
     bool received_headers = false;
diff --git a/http2/adapter/data_source.h b/http2/adapter/data_source.h
index d8d507b..b7f1afa 100644
--- a/http2/adapter/data_source.h
+++ b/http2/adapter/data_source.h
@@ -5,12 +5,13 @@
 #include <utility>
 
 #include "absl/strings/string_view.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
 // Represents a source of DATA frames for transmission to the peer.
-class DataFrameSource {
+class QUICHE_EXPORT_PRIVATE DataFrameSource {
  public:
   virtual ~DataFrameSource() {}
 
diff --git a/http2/adapter/http2_adapter.h b/http2/adapter/http2_adapter.h
index 32a9ba1..75eb138 100644
--- a/http2/adapter/http2_adapter.h
+++ b/http2/adapter/http2_adapter.h
@@ -8,6 +8,7 @@
 #include "http2/adapter/http2_protocol.h"
 #include "http2/adapter/http2_session.h"
 #include "http2/adapter/http2_visitor_interface.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
@@ -18,7 +19,7 @@
 // invokes corresponding callbacks on its passed-in Http2VisitorInterface.
 // Http2Adapter is a base class shared between client-side and server-side
 // implementations.
-class Http2Adapter {
+class QUICHE_EXPORT_PRIVATE Http2Adapter {
  public:
   Http2Adapter(const Http2Adapter&) = delete;
   Http2Adapter& operator=(const Http2Adapter&) = delete;
diff --git a/http2/adapter/http2_protocol.h b/http2/adapter/http2_protocol.h
index f2fc788..71a6db6 100644
--- a/http2/adapter/http2_protocol.h
+++ b/http2/adapter/http2_protocol.h
@@ -9,6 +9,7 @@
 #include "absl/base/attributes.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/variant.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
@@ -34,7 +35,7 @@
 using Header = std::pair<HeaderRep, HeaderRep>;
 
 // Represents an HTTP/2 SETTINGS key-value parameter.
-struct Http2Setting {
+QUICHE_EXPORT_PRIVATE struct Http2Setting {
   Http2SettingsId id;
   uint32_t value;
 };
@@ -56,11 +57,16 @@
 
 // The pseudo-header fields as specified in RFC 7540 Section 8.1.2.3 (request)
 // and Section 8.1.2.4 (response).
-ABSL_CONST_INIT extern const char kHttp2MethodPseudoHeader[];
-ABSL_CONST_INIT extern const char kHttp2SchemePseudoHeader[];
-ABSL_CONST_INIT extern const char kHttp2AuthorityPseudoHeader[];
-ABSL_CONST_INIT extern const char kHttp2PathPseudoHeader[];
-ABSL_CONST_INIT extern const char kHttp2StatusPseudoHeader[];
+ABSL_CONST_INIT QUICHE_EXPORT_PRIVATE extern const char
+    kHttp2MethodPseudoHeader[];
+ABSL_CONST_INIT QUICHE_EXPORT_PRIVATE extern const char
+    kHttp2SchemePseudoHeader[];
+ABSL_CONST_INIT QUICHE_EXPORT_PRIVATE extern const char
+    kHttp2AuthorityPseudoHeader[];
+ABSL_CONST_INIT QUICHE_EXPORT_PRIVATE extern const char
+    kHttp2PathPseudoHeader[];
+ABSL_CONST_INIT QUICHE_EXPORT_PRIVATE extern const char
+    kHttp2StatusPseudoHeader[];
 
 enum class FrameType : uint8_t {
   DATA = 0x0,
diff --git a/http2/adapter/http2_session.h b/http2/adapter/http2_session.h
index 0a6321c..49e671d 100644
--- a/http2/adapter/http2_session.h
+++ b/http2/adapter/http2_session.h
@@ -5,14 +5,15 @@
 
 #include "absl/strings/string_view.h"
 #include "http2/adapter/http2_protocol.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
-struct Http2SessionCallbacks {};
+QUICHE_EXPORT_PRIVATE struct Http2SessionCallbacks {};
 
 // A class to represent the state of a single HTTP/2 connection.
-class Http2Session {
+class QUICHE_EXPORT_PRIVATE Http2Session {
  public:
   Http2Session() = default;
   virtual ~Http2Session() {}
diff --git a/http2/adapter/http2_util.h b/http2/adapter/http2_util.h
index 3ace28b..88e9a49 100644
--- a/http2/adapter/http2_util.h
+++ b/http2/adapter/http2_util.h
@@ -2,13 +2,16 @@
 #define QUICHE_HTTP2_ADAPTER_HTTP2_UTIL_H_
 
 #include "http2/adapter/http2_protocol.h"
+#include "common/platform/api/quiche_export.h"
 #include "spdy/core/spdy_protocol.h"
 
 namespace http2 {
 namespace adapter {
 
-spdy::SpdyErrorCode TranslateErrorCode(Http2ErrorCode code);
-Http2ErrorCode TranslateErrorCode(spdy::SpdyErrorCode code);
+QUICHE_EXPORT_PRIVATE spdy::SpdyErrorCode TranslateErrorCode(
+    Http2ErrorCode code);
+QUICHE_EXPORT_PRIVATE Http2ErrorCode
+TranslateErrorCode(spdy::SpdyErrorCode code);
 
 }  // namespace adapter
 }  // namespace http2
diff --git a/http2/adapter/http2_visitor_interface.h b/http2/adapter/http2_visitor_interface.h
index e3f7c53..2a74ff5 100644
--- a/http2/adapter/http2_visitor_interface.h
+++ b/http2/adapter/http2_visitor_interface.h
@@ -5,6 +5,7 @@
 
 #include "absl/strings/string_view.h"
 #include "http2/adapter/http2_protocol.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
@@ -44,7 +45,7 @@
 //     - OnCloseStream()
 //
 // More details are at RFC 7540 (go/http2spec).
-class Http2VisitorInterface {
+class QUICHE_EXPORT_PRIVATE Http2VisitorInterface {
  public:
   Http2VisitorInterface(const Http2VisitorInterface&) = delete;
   Http2VisitorInterface& operator=(const Http2VisitorInterface&) = delete;
diff --git a/http2/adapter/mock_http2_visitor.h b/http2/adapter/mock_http2_visitor.h
index ca46e90..264c34e 100644
--- a/http2/adapter/mock_http2_visitor.h
+++ b/http2/adapter/mock_http2_visitor.h
@@ -2,6 +2,7 @@
 #define QUICHE_HTTP2_ADAPTER_MOCK_HTTP2_VISITOR_INTERFACE_H_
 
 #include "http2/adapter/http2_visitor_interface.h"
+#include "common/platform/api/quiche_export.h"
 #include "common/platform/api/quiche_test.h"
 
 namespace http2 {
@@ -9,7 +10,7 @@
 namespace test {
 
 // A mock visitor class, for use in tests.
-class MockHttp2Visitor : public Http2VisitorInterface {
+class QUICHE_NO_EXPORT MockHttp2Visitor : public Http2VisitorInterface {
  public:
   MockHttp2Visitor() {
     ON_CALL(*this, OnHeaderForStream).WillByDefault(testing::Return(HEADER_OK));
diff --git a/http2/adapter/mock_nghttp2_callbacks.h b/http2/adapter/mock_nghttp2_callbacks.h
index 1e8dc64..08d15be 100644
--- a/http2/adapter/mock_nghttp2_callbacks.h
+++ b/http2/adapter/mock_nghttp2_callbacks.h
@@ -4,6 +4,7 @@
 #include "absl/strings/string_view.h"
 #include "http2/adapter/nghttp2_util.h"
 #include "third_party/nghttp2/src/lib/includes/nghttp2/nghttp2.h"
+#include "common/platform/api/quiche_export.h"
 #include "common/platform/api/quiche_test.h"
 
 namespace http2 {
@@ -12,7 +13,7 @@
 
 // This class provides a set of mock nghttp2 callbacks for use in unit test
 // expectations.
-class MockNghttp2Callbacks {
+class QUICHE_NO_EXPORT MockNghttp2Callbacks {
  public:
   MockNghttp2Callbacks() = default;
 
diff --git a/http2/adapter/nghttp2_adapter.h b/http2/adapter/nghttp2_adapter.h
index b9900dd..2f2cbad 100644
--- a/http2/adapter/nghttp2_adapter.h
+++ b/http2/adapter/nghttp2_adapter.h
@@ -6,11 +6,12 @@
 #include "http2/adapter/http2_protocol.h"
 #include "http2/adapter/nghttp2_session.h"
 #include "http2/adapter/nghttp2_util.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
-class NgHttp2Adapter : public Http2Adapter {
+class QUICHE_EXPORT_PRIVATE NgHttp2Adapter : public Http2Adapter {
  public:
   ~NgHttp2Adapter() override;
 
diff --git a/http2/adapter/nghttp2_session.h b/http2/adapter/nghttp2_session.h
index 5dd08f8..4339875 100644
--- a/http2/adapter/nghttp2_session.h
+++ b/http2/adapter/nghttp2_session.h
@@ -4,12 +4,13 @@
 #include "http2/adapter/http2_session.h"
 #include "http2/adapter/nghttp2_util.h"
 #include "third_party/nghttp2/src/lib/includes/nghttp2/nghttp2.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
 // A C++ wrapper around common nghttp2_session operations.
-class NgHttp2Session : public Http2Session {
+class QUICHE_EXPORT_PRIVATE NgHttp2Session : public Http2Session {
  public:
   // Does not take ownership of |options|.
   NgHttp2Session(Perspective perspective,
diff --git a/http2/adapter/nghttp2_test_utils.h b/http2/adapter/nghttp2_test_utils.h
index dae3493..3ae63d3 100644
--- a/http2/adapter/nghttp2_test_utils.h
+++ b/http2/adapter/nghttp2_test_utils.h
@@ -6,6 +6,7 @@
 #include "absl/strings/string_view.h"
 #include "http2/adapter/http2_protocol.h"
 #include "third_party/nghttp2/src/lib/includes/nghttp2/nghttp2.h"
+#include "common/platform/api/quiche_export.h"
 #include "common/platform/api/quiche_test.h"
 
 namespace http2 {
@@ -13,7 +14,7 @@
 namespace test {
 
 // A simple class that can easily be adapted to act as a nghttp2_data_source.
-class TestDataSource {
+class QUICHE_NO_EXPORT TestDataSource {
  public:
   explicit TestDataSource(absl::string_view data) : data_(std::string(data)) {}
 
diff --git a/http2/adapter/oghttp2_adapter.h b/http2/adapter/oghttp2_adapter.h
index e2ea402..ace8ea9 100644
--- a/http2/adapter/oghttp2_adapter.h
+++ b/http2/adapter/oghttp2_adapter.h
@@ -6,11 +6,12 @@
 #include "http2/adapter/http2_adapter.h"
 #include "http2/adapter/http2_session.h"
 #include "http2/adapter/oghttp2_session.h"
+#include "common/platform/api/quiche_export.h"
 
 namespace http2 {
 namespace adapter {
 
-class OgHttp2Adapter : public Http2Adapter {
+class QUICHE_EXPORT_PRIVATE OgHttp2Adapter : public Http2Adapter {
  public:
   using Options = OgHttp2Session::Options;
   static std::unique_ptr<OgHttp2Adapter> Create(Http2VisitorInterface& visitor,
diff --git a/http2/adapter/oghttp2_session.h b/http2/adapter/oghttp2_session.h
index bd1a40a..70b0619 100644
--- a/http2/adapter/oghttp2_session.h
+++ b/http2/adapter/oghttp2_session.h
@@ -10,6 +10,7 @@
 #include "http2/adapter/window_manager.h"
 #include "http2/core/priority_write_scheduler.h"
 #include "common/platform/api/quiche_bug_tracker.h"
+#include "common/platform/api/quiche_export.h"
 #include "spdy/core/http2_frame_decoder_adapter.h"
 #include "spdy/core/spdy_framer.h"
 
@@ -17,10 +18,11 @@
 namespace adapter {
 
 // This class manages state associated with a single multiplexed HTTP/2 session.
-class OgHttp2Session : public Http2Session,
-                       public spdy::SpdyFramerVisitorInterface {
+class QUICHE_EXPORT_PRIVATE OgHttp2Session
+    : public Http2Session,
+      public spdy::SpdyFramerVisitorInterface {
  public:
-  struct Options {
+  QUICHE_EXPORT_PRIVATE struct Options {
     Perspective perspective = Perspective::kClient;
   };
 
@@ -150,7 +152,7 @@
                       Http2VisitorInterface::OnHeaderResult result);
 
  private:
-  struct StreamState {
+  QUICHE_EXPORT_PRIVATE struct StreamState {
     StreamState(int32_t stream_receive_window,
                 WindowManager::WindowUpdateListener listener)
         : window_manager(stream_receive_window, std::move(listener)) {}
@@ -164,7 +166,8 @@
     bool half_closed_remote = false;
   };
 
-  class PassthroughHeadersHandler : public spdy::SpdyHeadersHandlerInterface {
+  class QUICHE_EXPORT_PRIVATE PassthroughHeadersHandler
+      : public spdy::SpdyHeadersHandlerInterface {
    public:
     explicit PassthroughHeadersHandler(OgHttp2Session& session,
                                        Http2VisitorInterface& visitor)
diff --git a/http2/adapter/oghttp2_util.h b/http2/adapter/oghttp2_util.h
index e222c96..3134ff7 100644
--- a/http2/adapter/oghttp2_util.h
+++ b/http2/adapter/oghttp2_util.h
@@ -3,12 +3,14 @@
 
 #include "absl/types/span.h"
 #include "http2/adapter/http2_protocol.h"
+#include "common/platform/api/quiche_export.h"
 #include "spdy/core/spdy_header_block.h"
 
 namespace http2 {
 namespace adapter {
 
-spdy::SpdyHeaderBlock ToHeaderBlock(absl::Span<const Header> headers);
+QUICHE_EXPORT_PRIVATE spdy::SpdyHeaderBlock ToHeaderBlock(
+    absl::Span<const Header> headers);
 
 }  // namespace adapter
 }  // namespace http2
diff --git a/http2/adapter/recording_http2_visitor.h b/http2/adapter/recording_http2_visitor.h
index 62ce651..501a476 100644
--- a/http2/adapter/recording_http2_visitor.h
+++ b/http2/adapter/recording_http2_visitor.h
@@ -5,6 +5,7 @@
 #include <string>
 
 #include "http2/adapter/http2_visitor_interface.h"
+#include "common/platform/api/quiche_export.h"
 #include "common/platform/api/quiche_test.h"
 
 namespace http2 {
@@ -12,7 +13,7 @@
 namespace test {
 
 // A visitor implementation that records the sequence of callbacks it receives.
-class RecordingHttp2Visitor : public Http2VisitorInterface {
+class QUICHE_NO_EXPORT RecordingHttp2Visitor : public Http2VisitorInterface {
  public:
   using Event = std::string;
   using EventSequence = std::list<Event>;
diff --git a/http2/adapter/test_frame_sequence.h b/http2/adapter/test_frame_sequence.h
index 7a65f67..4496614 100644
--- a/http2/adapter/test_frame_sequence.h
+++ b/http2/adapter/test_frame_sequence.h
@@ -6,16 +6,17 @@
 #include <vector>
 
 #include "http2/adapter/http2_protocol.h"
+#include "common/platform/api/quiche_export.h"
 #include "spdy/core/spdy_protocol.h"
 
 namespace http2 {
 namespace adapter {
 namespace test {
 
-std::vector<const Header> ToHeaders(
+std::vector<const Header> QUICHE_NO_EXPORT ToHeaders(
     absl::Span<const std::pair<absl::string_view, absl::string_view>> headers);
 
-class TestFrameSequence {
+class QUICHE_NO_EXPORT TestFrameSequence {
  public:
   TestFrameSequence() = default;
 
diff --git a/http2/adapter/test_utils.h b/http2/adapter/test_utils.h
index cea7d61..9cac22e 100644
--- a/http2/adapter/test_utils.h
+++ b/http2/adapter/test_utils.h
@@ -8,6 +8,7 @@
 #include "http2/adapter/data_source.h"
 #include "http2/adapter/http2_protocol.h"
 #include "http2/adapter/mock_http2_visitor.h"
+#include "common/platform/api/quiche_export.h"
 #include "common/platform/api/quiche_test.h"
 #include "spdy/core/spdy_protocol.h"
 
@@ -15,7 +16,8 @@
 namespace adapter {
 namespace test {
 
-class DataSavingVisitor : public testing::StrictMock<MockHttp2Visitor> {
+class QUICHE_NO_EXPORT DataSavingVisitor
+    : public testing::StrictMock<MockHttp2Visitor> {
  public:
   ssize_t OnReadyToSend(absl::string_view data) override {
     if (is_write_blocked_) {
@@ -42,7 +44,7 @@
 
 // A test DataFrameSource that can be initialized with a single string payload,
 // or a chunked payload.
-class TestDataFrameSource : public DataFrameSource {
+class QUICHE_NO_EXPORT TestDataFrameSource : public DataFrameSource {
  public:
   TestDataFrameSource(Http2VisitorInterface& visitor,
                       absl::string_view data_payload,
diff --git a/http2/adapter/window_manager.h b/http2/adapter/window_manager.h
index 277c24f..f15982d 100644
--- a/http2/adapter/window_manager.h
+++ b/http2/adapter/window_manager.h
@@ -3,6 +3,8 @@
 
 #include <functional>
 
+#include "common/platform/api/quiche_export.h"
+
 namespace http2 {
 namespace adapter {
 
@@ -12,7 +14,7 @@
 
 // This class keeps track of a HTTP/2 flow control window, notifying a listener
 // when a window update needs to be sent. This class is not thread-safe.
-class WindowManager {
+class QUICHE_EXPORT_PRIVATE WindowManager {
  public:
   // A WindowUpdateListener is invoked when it is time to send a window update.
   typedef std::function<void(size_t)> WindowUpdateListener;
diff --git a/spdy/core/spdy_protocol.h b/spdy/core/spdy_protocol.h
index d7d0e8b..651a889 100644
--- a/spdy/core/spdy_protocol.h
+++ b/spdy/core/spdy_protocol.h
@@ -260,7 +260,7 @@
     SpdyFrameType frame_type_field);
 
 // Serialize |frame_type| to string for logging/debugging.
-const char* FrameTypeToString(SpdyFrameType frame_type);
+QUICHE_EXPORT_PRIVATE const char* FrameTypeToString(SpdyFrameType frame_type);
 
 // If |wire_setting_id| is the on-the-wire representation of a defined SETTINGS
 // parameter, parse it to |*setting_id| and return true.
@@ -328,7 +328,7 @@
 // Initial window size for a session in bytes.
 const int32_t kInitialSessionWindowSize = 64 * 1024 - 1;
 // The NPN string for HTTP2, "h2".
-extern const char* const kHttp2Npn;
+QUICHE_EXPORT_PRIVATE extern const char* const kHttp2Npn;
 // An estimate size of the HPACK overhead for each header field. 1 bytes for
 // indexed literal, 1 bytes for key literal and length encoding, and 2 bytes for
 // value literal and length encoding.
@@ -351,7 +351,7 @@
 // exclusive bit}. Templated to allow for use by QUIC code; SPDY and HTTP/2
 // code should use the concrete type instantiation SpdyStreamPrecedence.
 template <typename StreamIdType>
-class StreamPrecedence {
+QUICHE_EXPORT_PRIVATE class StreamPrecedence {
  public:
   // Constructs instance that is a SPDY 3.x priority. Clamps priority value to
   // the valid range [0, 7].
@@ -427,7 +427,7 @@
   }
 
  private:
-  struct Http2StreamDependency {
+  QUICHE_EXPORT_PRIVATE struct Http2StreamDependency {
     StreamIdType parent_id;
     int weight;
     bool is_exclusive;
@@ -920,7 +920,7 @@
   std::string priority_field_value_;
 };
 
-struct AcceptChOriginValuePair {
+QUICHE_EXPORT_PRIVATE struct AcceptChOriginValuePair {
   std::string origin;
   std::string value;
   bool operator==(const AcceptChOriginValuePair& rhs) const {