Refactor GL bindings so there is no global GLApi or DriverGL.

gpu/command_buffer/service/memory_program_cache.cc

Index: gpu/command_buffer/service/memory_program_cache.cc
diff --git a/gpu/command_buffer/service/memory_program_cache.cc b/gpu/command_buffer/service/memory_program_cache.cc
index 410914db2b0d1941ee209ce27d7b5d721077aadc..b24cbd7e42f74149e8d804f9ad973b165c91a95b 100644
--- a/gpu/command_buffer/service/memory_program_cache.cc
+++ b/gpu/command_buffer/service/memory_program_cache.cc
@@ -200,6 +200,12 @@ void RunShaderCallback(const ShaderCacheCallback& callback,
   callback.Run(key, shader);
 }
 
+bool ProgramBinaryExtensionsAvailable() {
+  return gl::g_current_gl_driver &&
+         (gl::g_current_gl_driver->ext.b_GL_ARB_get_program_binary ||
+          gl::g_current_gl_driver->ext.b_GL_OES_get_program_binary);
+}
+
 }  // namespace
 
 MemoryProgramCache::MemoryProgramCache(
@@ -229,6 +235,11 @@ ProgramCache::ProgramLoadResult MemoryProgramCache::LoadLinkedProgram(
     const std::vector<std::string>& transform_feedback_varyings,
     GLenum transform_feedback_buffer_mode,
     const ShaderCacheCallback& shader_callback) {
+  if (!ProgramBinaryExtensionsAvailable()) {

[jbauman, 2017/01/18 21:32:09]

Why is this in this patch?

[Geoff Lang, 2017/01/19 15:40:06]

I found that the order of operations for the program cache is:
 - GPU info collection occurs, creates a context, initializes the global
DriverGL and destroys the context
 - Cached program binaries start being fed to the gpu process, cache is created
based on state of the DriverGL

This caused problems because there was no context bound when the program
binaries started arriving.  Now I create the program cache without extension
checks, it's unlikely that we have cached binaries if the extensions were never
present to begin with.  The extension checks are now done right before
loading/saving binaries which makes sure that the current context is capable of
using binaries.

+    // Early exit if this context can't support program binaries
+    return PROGRAM_LOAD_FAILURE;
+  }
+
   char a_sha[kHashLength];
   char b_sha[kHashLength];
   DCHECK(shader_a && !shader_a->last_compiled_source().empty() &&
@@ -295,6 +306,10 @@ void MemoryProgramCache::SaveLinkedProgram(
     const std::vector<std::string>& transform_feedback_varyings,
     GLenum transform_feedback_buffer_mode,
     const ShaderCacheCallback& shader_callback) {
+  if (!ProgramBinaryExtensionsAvailable()) {
+    // Early exit if this context can't support program binaries
+    return;
+  }
   if (disable_program_caching_for_transform_feedback_ &&
       !transform_feedback_varyings.empty()) {
     return;