command_buffer: Implement glGetStringi for GL ES 3.0

gpu/command_buffer/client/gles2_implementation.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_H_
 #define GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 672 matching lines @@
   void CheckGLError() { }
   void FailGLError(GLenum /* error */) { }
 #endif
 
   void RemoveMappedBufferRangeByTarget(GLenum target);
   void RemoveMappedBufferRangeById(GLuint buffer);
   void ClearMappedBufferRangeMap();
 
   void DrawElementsImpl(GLenum mode, GLsizei count, GLenum type,
                         const void* indices, const char* func_name);
+  void UpdateCachedExtensionsIfNeeded();
+  void InvalidateCachedExtensions();
 
   GLES2Util util_;
   GLES2CmdHelper* helper_;
   TransferBufferInterface* transfer_buffer_;
   std::string last_error_;
   DebugMarkerManager debug_marker_manager_;
   std::string this_in_hex_;
 
   std::queue<int32_t> swap_buffers_tokens_;
   std::queue<int32_t> rate_limit_tokens_;
@@ skipping 78 matching lines @@
 
   // Used to check for single threaded access.
   int use_count_;
 
   // Maximum amount of extra memory from the mapped memory pool to use when
   // needing to transfer something exceeding the default transfer buffer.
   // This should be 0 for low memory devices since they are already memory
   // constrained.
   const uint32_t max_extra_transfer_buffer_size_;
 
-  // Map of GLenum to Strings for glGetString.  We need to cache these because
+  // Set of strings returned from glGetString.  We need to cache these because
   // the pointer passed back to the client has to remain valid for eternity.
-  typedef std::map<uint32_t, std::set<std::string>> GLStringMap;
-  GLStringMap gl_strings_;
-
-  // Similar cache for glGetRequestableExtensionsCHROMIUM. We don't
-  // have an enum for this so handle it separately.
-  std::set<std::string> requestable_extensions_set_;
+  std::set<std::string> gl_strings_;
 
   typedef std::map<const void*, MappedBuffer> MappedBufferMap;
   MappedBufferMap mapped_buffers_;
 
   // TODO(zmo): Consolidate |mapped_buffers_| and |mapped_buffer_range_map_|.
   typedef base::hash_map<GLuint, MappedBuffer> MappedBufferRangeMap;
   MappedBufferRangeMap mapped_buffer_range_map_;
 
   typedef std::map<const void*, MappedTexture> MappedTextureMap;
   MappedTextureMap mapped_textures_;
@@ skipping 13 matching lines @@
   int current_trace_stack_;
 
   GpuControl* gpu_control_;
 
   Capabilities capabilities_;
 
   // Flag to indicate whether the implementation can retain resources, or
   // whether it should aggressively free them.
   bool aggressively_free_resources_;
 
+  // Result of last GetString(GL_EXTENSIONS), used to keep
+  // GetString(GL_EXTENSIONS), GetStringi(GL_EXTENSIONS, index) and
+  // GetIntegerv(GL_NUM_EXTENSIONS) in sync. This points to gl_strings, valid
+  // forever.
+  const char* cached_extension_string_;
+
+  // Populated if cached_extension_string_ != nullptr. These point to
+  // gl_strings, valid forever.
+  std::vector<const char*> cached_extensions_;
+
   base::WeakPtrFactory<GLES2Implementation> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLES2Implementation);
 };
 
 inline bool GLES2Implementation::GetBufferParameteri64vHelper(
     GLenum /* target */, GLenum /* pname */, GLint64* /* params */) {
   return false;
 }
 
@@ skipping 27 matching lines @@
 
 inline bool GLES2Implementation::GetTexParameterivHelper(
     GLenum /* target */, GLenum /* pname */, GLint* /* params */) {
   return false;
 }
 
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_CLIENT_GLES2_IMPLEMENTATION_H_