Add EGL_ARM_implicit_external_sync extension support

And use it to flush rendering before page flip.

BUG=412508,442605
TEST=build and run Chrome on jerry/freon. It should render one frame.
R=alexst@chromium.org
R=dnicoara@chromium.org
R=kbr@chromium.org
R=piman@chromium.org
Signed-off-by: Dominik Behr <dbehr@chromium.org>

Review URL: https://codereview.chromium.org/903063003

Cr-Commit-Position: refs/heads/master@{#315171}

third_party/khronos/EGL/eglext.h

@@ -563,6 +563,11 @@ typedef EGLint (EGLAPIENTRYP PFNEGLDUPNATIVEFENCEFDANDROIDPROC)(EGLDisplay dpy,
 #define EGL_YUV_CHROMA_SITING_0_5_EXT		0x3285
 #endif
 
+#ifndef EGL_ARM_implicit_external_sync
+#define EGL_ARM_implicit_external_sync 1
+#define EGL_SYNC_PRIOR_COMMANDS_IMPLICIT_EXTERNAL_ARM 0x328A
+#endif /* EGL_ARM_implicit_external_sync */
+
 #ifdef __cplusplus
 }
 #endif

third_party/khronos/README.chromium

@@ -33,6 +33,8 @@ GLES2/gl2ext.h
 EGL/eglplatform.h
  - Added EGLNative*Type for Mac.
  - Added EGLNative*Type for native linux framebuffers.
+EGL/eglext.h
+ - Added EGL_ARM_implicit_external_sync extension tokens
 KHR/khrplatform.h
  - Modified KHRONOS_APICALL and KHRONOS_APIENTRY
 DEPS

ui/gl/gl_surface_ozone.cc

@@ -105,7 +105,9 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
                             AcceleratedWidget widget)
       : SurfacelessEGL(gfx::Size()),
         ozone_surface_(ozone_surface.Pass()),
-        widget_(widget) {}
+        widget_(widget),
+        has_implicit_external_sync_(
+            HasEGLExtension("EGL_ARM_implicit_external_sync")) {}
 
   bool Initialize() override {
     if (!SurfacelessEGL::Initialize())
@@ -122,8 +124,8 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
     return SurfacelessEGL::Resize(size);
   }
   bool SwapBuffers() override {
-    // TODO: this should be replaced by a fence when supported by the driver.
-    glFlush();
+    if (!Flush())
+      return false;
     return ozone_surface_->OnSwapBuffers();
   }
   bool ScheduleOverlayPlane(int z_order,
@@ -143,8 +145,8 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
     return true;
   }
   bool SwapBuffersAsync(const SwapCompletionCallback& callback) override {
-    // TODO: this should be replaced by a fence when supported by the driver.
-    glFlush();
+    if (!Flush())
+      return false;
     return ozone_surface_->OnSwapBuffersAsync(callback);
   }
   bool PostSubBufferAsync(int x,
@@ -160,11 +162,35 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
     Destroy();  // EGL surface must be destroyed before SurfaceOzone
   }
 
+  bool Flush() {
+    glFlush();
+    // TODO: the following should be replaced by a per surface flush as it gets
+    // implemented in GL drivers.
+    if (has_implicit_external_sync_) {
+      const EGLint attrib_list[] = {
+          EGL_SYNC_CONDITION_KHR,
+          EGL_SYNC_PRIOR_COMMANDS_IMPLICIT_EXTERNAL_ARM,
+          EGL_NONE};
+      EGLSyncKHR fence =
+          eglCreateSyncKHR(GetDisplay(), EGL_SYNC_FENCE_KHR, attrib_list);
+      if (fence) {
+        // TODO(dbehr): piman@ suggests we could improve here by moving
+        // following wait to right before drmModePageFlip crbug.com/456417.
+        eglClientWaitSyncKHR(GetDisplay(), fence,
+                             EGL_SYNC_FLUSH_COMMANDS_BIT_KHR, EGL_FOREVER_KHR);
+        eglDestroySyncKHR(GetDisplay(), fence);
+      } else {
+        return false;
+      }
+    }
+    return true;
+  }
+
   // The native surface. Deleting this is allowed to free the EGLNativeWindow.
   scoped_ptr<ui::SurfaceOzoneEGL> ozone_surface_;
   AcceleratedWidget widget_;
   scoped_ptr<VSyncProvider> vsync_provider_;
-
+  bool has_implicit_external_sync_;
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceOzoneSurfaceless);
 };