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

1 files changed, 16 insertions, 8 deletions

diff --git a/src/gpu/gl/win/SkCreatePlatformGLContext_win.cpp b/src/gpu/gl/win/SkCreatePlatformGLContext_win.cpp
index d387ef4922..8a4c5db5b3 100644
--- a/src/gpu/gl/win/SkCreatePlatformGLContext_win.cpp
+++ b/src/gpu/gl/win/SkCreatePlatformGLContext_win.cpp
@@ -21,12 +21,14 @@ class WinGLContext : public SkGLContext {
 public:
     WinGLContext(GrGLStandard forcedGpuAPI);
 	~WinGLContext() override;
-    void makeCurrent() const override;
-    void swapBuffers() const override;
 
 private:
     void destroyGLContext();
 
+    void onPlatformMakeCurrent() const override;
+    void onPlatformSwapBuffers() const override;
+    GrGLFuncPtr onPlatformGetProcAddress(const char* name) const override;
+
     HWND fWindow;
     HDC fDeviceContext;
     HGLRC fGlRenderContext;
@@ -113,25 +115,27 @@ WinGLContext::WinGLContext(GrGLStandard forcedGpuAPI)
         return;
     }
 
-    fGL.reset(GrGLCreateNativeInterface());
-    if (NULL == fGL.get()) {
+    SkAutoTUnref<const GrGLInterface> gl(GrGLCreateNativeInterface());
+    if (NULL == gl.get()) {
         SkDebugf("Could not create GL interface.\n");
         this->destroyGLContext();
         return;
     }
-    if (!fGL->validate()) {
+    if (!gl->validate()) {
         SkDebugf("Could not validate GL interface.\n");
         this->destroyGLContext();
         return;
     }
+
+    this->init(gl.detach());
 }
 
 WinGLContext::~WinGLContext() {
+    this->teardown();
     this->destroyGLContext();
 }
 
 void WinGLContext::destroyGLContext() {
-    fGL.reset(NULL);
     SkSafeSetNull(fPbufferContext);
     if (fGlRenderContext) {
         wglDeleteContext(fGlRenderContext);
@@ -147,7 +151,7 @@ void WinGLContext::destroyGLContext() {
     }
 }
 
-void WinGLContext::makeCurrent() const {
+void WinGLContext::onPlatformMakeCurrent() const {
     HDC dc;
     HGLRC glrc;
 
@@ -164,7 +168,7 @@ void WinGLContext::makeCurrent() const {
     }
 }
 
-void WinGLContext::swapBuffers() const {
+void WinGLContext::onPlatformSwapBuffers() const {
     HDC dc;
 
     if (NULL == fPbufferContext) {
@@ -177,6 +181,10 @@ void WinGLContext::swapBuffers() const {
     }
 }
 
+GrGLFuncPtr WinGLContext::onPlatformGetProcAddress(const char* name) const {
+    return reinterpret_cast<GrGLFuncPtr>(wglGetProcAddress(name));
+}
+
 } // anonymous namespace
 
 SkGLContext* SkCreatePlatformGLContext(GrGLStandard forcedGpuAPI) {