Implement basic query functionality in the passthrough command buffer.

gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h

Index: gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h
index ba64f064f9acb416f8f6f40e475bcf5985458861..05c70693791ff5d76091a2f23ca4bed1378b4f61 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.h
@@ -280,6 +280,13 @@ class GLES2DecoderPassthroughImpl : public GLES2Decoder {
 
   void BuildExtensionsString();
 
+  void InsertError(GLenum error, const std::string& message);
+  GLenum PopError();
+  bool FlushErrors();
+
+  bool IsEmulatedQueryTarget(GLenum target) const;
+  error::Error ProcessQueries(bool did_finish);
+
   int commands_to_process_;
 
   DebugMarkerManager debug_marker_manager_;
@@ -342,6 +349,33 @@ class GLES2DecoderPassthroughImpl : public GLES2Decoder {
   size_t active_texture_unit_;
   std::vector<GLuint> bound_textures_;
 
+  // Track the service-id to type of all queries for validation
+  struct QueryInfo {
+    GLenum type = GL_NONE;
+  };
+  std::unordered_map<GLuint, QueryInfo> query_info_map_;
+
+  // All queries that are waiting for their results to be ready
+  struct PendingQuery {
+    GLenum target = GL_NONE;
+    GLuint service_id = 0;
+
+    int32_t shm_id = 0;
+    uint32_t shm_offset = 0;
+    base::subtle::Atomic32 submit_count = 0;
+  };
+  std::deque<PendingQuery> pending_queries_;
+
+  // Currently active queries
+  struct ActiveQuery {
+    GLuint service_id = 0;
+    int32_t shm_id = 0;
+    uint32_t shm_offset = 0;
+  };
+  std::unordered_map<GLenum, ActiveQuery> active_queries_;
+
+  std::set<GLenum> errors_;
+
   std::vector<std::string> emulated_extensions_;
   std::string extension_string_;