Implement SkGLContext swapBuffers with fence syncs

Improves the GPU measuring accuracy of nanobench by using fence syncs.
Fence syncs are very widely supported and available on almost every
platform.

NO_MERGE_BUILDS
BUG=skia:

Review URL: https://codereview.chromium.org/1194783003

2 files changed, 6 insertions, 4 deletions

diff --git a/src/gpu/gl/debug/SkDebugGLContext.cpp b/src/gpu/gl/debug/SkDebugGLContext.cpp
index ae55104d46..531e6c3ab8 100644
--- a/src/gpu/gl/debug/SkDebugGLContext.cpp
+++ b/src/gpu/gl/debug/SkDebugGLContext.cpp
@@ -9,9 +9,9 @@
 #include "gl/debug/SkDebugGLContext.h"
 
 SkDebugGLContext::SkDebugGLContext() {
-    fGL.reset(GrGLCreateDebugInterface());
+    this->init(GrGLCreateDebugInterface());
 }
 
 SkDebugGLContext::~SkDebugGLContext() {
-    fGL.reset(NULL);
+    this->teardown();
 }
diff --git a/src/gpu/gl/debug/SkDebugGLContext.h b/src/gpu/gl/debug/SkDebugGLContext.h
index 577953223a..6a4d9fc38b 100644
--- a/src/gpu/gl/debug/SkDebugGLContext.h
+++ b/src/gpu/gl/debug/SkDebugGLContext.h
@@ -13,8 +13,6 @@
 class SkDebugGLContext : public SkGLContext {
 public:
     ~SkDebugGLContext() override;
-    void makeCurrent() const override {}
-    void swapBuffers() const override {}
 
     static SkDebugGLContext* Create(GrGLStandard forcedGpuAPI) {
         if (kGLES_GrGLStandard == forcedGpuAPI) {
@@ -23,6 +21,10 @@ public:
         return SkNEW(SkDebugGLContext);
     }
 private:
+    void onPlatformMakeCurrent() const override {}
+    void onPlatformSwapBuffers() const override {}
+    GrGLFuncPtr onPlatformGetProcAddress(const char*) const override { return NULL; }
+
     SkDebugGLContext();
 };