Remove generate_from_pos since there's no user of it

As titled

Author: larryliu0820

examples/mediatek/executor_runner/mtk_llama_runner.h

@@ -66,6 +66,8 @@ class MTKLlamaRunner : public executorch::extension::llm::IRunner {
       std::function<void(const std::string&)> token_callback);
   std::unique_ptr<Tokenizer> load_tokenizer();
 
+  void reset() {}
+
  private:
   // model
   const LlamaModelOptions modeloptions_;

extension/llm/runner/irunner.h

@@ -125,39 +125,18 @@ class ET_EXPERIMENTAL IRunner {
       std::function<void(const std::string&)> token_callback,
       std::function<void(const Stats&)> stats_callback) = 0;
 
-  /**
-   * Generate text based on the provided prompt and generation config, from a
-   * given position in KV cache.
-   *
-   * @param prompt The input prompt to generate from
-   * @param start_pos The starting position in KV cache of the input. Note:
-   * Depending on the actual implementation, a runner may manage the position
-   * internally, and this may not be respected.
-   * @param config Generation configuration parameters
-   * @param token_callback Callback function called for each generated token
-   * @param stats_callback Callback function for generation statistics
-   * @return Error::Ok if successful, an error otherwise
-   */
-  virtual runtime::Error generate_from_pos(
-      const std::string& prompt,
-      int64_t start_pos,
-      const GenerationConfig& config,
-      std::function<void(const std::string&)> token_callback,
-      std::function<void(const Stats&)> stats_callback) = 0;
   /**
    * Stop the generation process.
    */
   virtual void stop() = 0;
+
   /**
    * Force remove prefilled tokens and reset KV cache start position
    *
-   * For some existing runners, overriding this method is not needed because
-   * start_pos is passed as an argument to generate_from_pos.
-   *
    * This method removes the prefilled tokens from the KV cache and resets the
    * start position to 0.
    */
-  virtual void reset() {};
+  virtual void reset() = 0;
 };
 
 } // namespace llm

extension/llm/runner/text_llm_runner.cpp

@@ -43,6 +43,7 @@ TextLLMRunner::TextLLMRunner(
       io_manager_(std::move(io_manager)),
       text_token_generator_(std::move(text_token_generator)),
       stats_(std::move(stats)),
+      pos_(0),
       temperature_(temperature) {
   // Note: This constructor assumes that text_prefiller and text_token_generator
   // already have references to the Module and TextDecoderRunner they need
@@ -70,9 +71,8 @@ Error TextLLMRunner::load() {
     ET_LOG(Info, format, __VA_ARGS__);     \
   }
 
-Error TextLLMRunner::generate_from_pos(
+Error TextLLMRunner::generate(
     const std::string& prompt,
-    ET_UNUSED int64_t start_pos,
     const GenerationConfig& config,
     std::function<void(const std::string&)> token_callback,
     std::function<void(const Stats&)> stats_callback) {
@@ -217,15 +217,6 @@ Error TextLLMRunner::generate_from_pos(
   return Error::Ok;
 }
 
-Error TextLLMRunner::generate(
-    const std::string& prompt,
-    const GenerationConfig& config,
-    std::function<void(const std::string&)> token_callback,
-    std::function<void(const Stats&)> stats_callback) {
-  pos_ = 0;
-  return generate_from_pos(prompt, 0, config, token_callback, stats_callback);
-}
-
 Error TextLLMRunner::warmup(const std::string& prompt, int32_t max_new_tokens) {
   // Create a GenerationConfig for warmup
   GenerationConfig config{

extension/llm/runner/text_llm_runner.h

@@ -101,25 +101,6 @@ class ET_EXPERIMENTAL TextLLMRunner : public IRunner {
       std::function<void(const std::string&)> token_callback = {},
       std::function<void(const Stats&)> stats_callback = {}) override;
 
-  /**
-   * Generate text based on the provided prompt and generation config, from a
-   * given position in KV cache.
-   *
-   * @param prompt The input prompt to generate from
-   * @param start_pos [Unused] The starting position in KV cache of the input,
-   * ignored because the runner manages the position internally.
-   * @param config Generation configuration parameters
-   * @param token_callback Callback function called for each generated token
-   * @param stats_callback Callback function for generation statistics
-   * @return Error::Ok if successful, an error otherwise
-   */
-  ET_DEPRECATED runtime::Error generate_from_pos(
-      const std::string& prompt,
-      ET_UNUSED int64_t start_pos,
-      const GenerationConfig& config,
-      std::function<void(const std::string&)> token_callback = {},
-      std::function<void(const Stats&)> stats_callback = {}) override;
-
   /**
    * @brief Warms up the model with a sample prompt
    *
@@ -133,13 +114,15 @@ class ET_EXPERIMENTAL TextLLMRunner : public IRunner {
   ::executorch::runtime::Error warmup(
       const std::string& prompt,
       int32_t max_new_tokens);
+
   /**
    * @brief Remove prefilled tokens and reset start position, and stats.
    *
    * This method removes the prefilled tokens from the KV cache and resets the
    * start position to 0. It also clears the stats for previous runs.
    */
   void reset() override;
+
   /**
    * @brief Stops the ongoing text generation process
    *