skiaserve no longer crashes when no X server is present

tools/skiaserve/Request.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Request.h"
 
 #include "SkPictureRecorder.h"
@@ skipping 53 matching lines @@
     SkDrawCommand::WritePNG((const png_bytep) encodedBitmap->writable_data(),
                             bmp->width(), bmp->height(),
                             buffer);
     return buffer.copyToData();
 }
 
 SkCanvas* Request::getCanvas() {
 #if SK_SUPPORT_GPU
     GrContextFactory* factory = fContextFactory;
     GLTestContext* gl = factory->getContextInfo(GrContextFactory::kNativeGL_ContextType,
-                                            GrContextFactory::kNone_ContextOptions).glContext();
-    gl->makeCurrent();
+                                                GrContextFactory::kNone_ContextOptions).glContext();
+    if (!gl) {
+        gl = factory->getContextInfo(GrContextFactory::kMESA_ContextType,
+                                     GrContextFactory::kNone_ContextOptions).glContext();
+    }
+    if (gl) {
+        gl->makeCurrent();
+    }
 #endif
     SkASSERT(fDebugCanvas);
 
     // create the appropriate surface if necessary
     if (!fSurface) {
         this->enableGPU(fGPUEnabled);
     }
     SkCanvas* target = fSurface->getCanvas();
     return target;
 }
@@ skipping 22 matching lines @@
     SkDynamicMemoryWStream outStream;
 
     SkAutoTUnref<SkPixelSerializer> serializer(SkImageEncoder::CreatePixelSerializer());
     picture->serialize(&outStream, serializer);
 
     return outStream.copyToData();
 }
 
 GrContext* Request::getContext() {
 #if SK_SUPPORT_GPU
-  return fContextFactory->get(GrContextFactory::kNativeGL_ContextType,
-                              GrContextFactory::kNone_ContextOptions);
+    GrContext* result = fContextFactory->get(GrContextFactory::kNativeGL_ContextType,
+                                             GrContextFactory::kNone_ContextOptions);
+    if (!result) {
+        result = fContextFactory->get(GrContextFactory::kMESA_ContextType,
+                                      GrContextFactory::kNone_ContextOptions);
+    } 
+    return result;
 #else
-  return nullptr;
+    return nullptr;
 #endif
 }
 
 SkIRect Request::getBounds() {
     SkIRect bounds;
     if (fPicture) {
         bounds = fPicture->cullRect().roundOut();
         if (fGPUEnabled) {
 #if SK_SUPPORT_GPU
             int maxRTSize = this->getContext()->caps()->maxRenderTargetSize();
@@ skipping 160 matching lines @@
     SkASSERT(bitmap);
 
     // Convert to format suitable for inspection
     sk_sp<SkData> encodedBitmap = sk_tools::encode_bitmap_for_png(*bitmap);
     SkASSERT(encodedBitmap.get());
 
     const uint8_t* start = encodedBitmap->bytes() + ((y * bitmap->width() + x) * 4);
     SkColor result = SkColorSetARGB(start[3], start[0], start[1], start[2]);
     return result;
 }