Only Destroy if context is current

This is a speculative fix for https://crbug.com/1022151. Based on the
crash error and stack trace, it seems likely that we are calling
ClearFramebufferResourceManager::Destroy after a context is unavailable
(i.e. released or lost). In this case, we shouldn't be making any more
GL calls. This copies a pattern of GLES2DecoderImpl::Destroy, so that
CFRM::Destroy is only called if we have a current context.

Bug: 1022151
Change-Id: Icc76e505fa32c3b3bc5bea68a973ac4550828bf5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1934519Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: Jonathan Backer <backer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718801}

gpu/command_buffer/service/gles2_cmd_clear_framebuffer.cc

@@ -47,10 +47,7 @@ ClearFramebufferResourceManager::ClearFramebufferResourceManager(
   Initialize(decoder);
 }
 
-ClearFramebufferResourceManager::~ClearFramebufferResourceManager() {
-  Destroy();
-  DCHECK(!buffer_id_);
-}
+ClearFramebufferResourceManager::~ClearFramebufferResourceManager() = default;
 
 void ClearFramebufferResourceManager::Initialize(
     const gles2::GLES2Decoder* decoder) {
@@ -77,7 +74,6 @@ void ClearFramebufferResourceManager::Destroy() {
 
   glDeleteProgram(program_);
   glDeleteBuffersARB(1, &buffer_id_);
-  buffer_id_ = 0;
 }
 
 void ClearFramebufferResourceManager::ClearFramebuffer(

gpu/command_buffer/service/gles2_cmd_clear_framebuffer.h

@@ -22,6 +22,7 @@ class GPU_GLES2_EXPORT ClearFramebufferResourceManager {
   ClearFramebufferResourceManager(const gles2::GLES2Decoder* decoder);
   ~ClearFramebufferResourceManager();
 
+  void Destroy();
   void ClearFramebuffer(const gles2::GLES2Decoder* decoder,
                         const gfx::Size& max_viewport_size,
                         GLbitfield mask,
@@ -34,7 +35,6 @@ class GPU_GLES2_EXPORT ClearFramebufferResourceManager {
 
  private:
   void Initialize(const gles2::GLES2Decoder* decoder);
-  void Destroy();
 
   // The attributes used during invocation of the extension.
   static const GLuint kVertexPositionAttrib = 0;

gpu/command_buffer/service/gles2_cmd_decoder.cc

@@ -5363,7 +5363,10 @@ void GLES2DecoderImpl::Destroy(bool have_context) {
       srgb_converter_.reset();
     }
 
-    clear_framebuffer_blit_.reset();
+    if (clear_framebuffer_blit_.get()) {
+      clear_framebuffer_blit_->Destroy();
+      clear_framebuffer_blit_.reset();
+    }
 
     if (state_.current_program.get()) {
       program_manager()->UnuseProgram(shader_manager(),