Improvements to uses of base::SmallMap

ui/ozone/platform/drm/common/drm_util.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/ozone/platform/drm/common/drm_util.h"
 
 #include <drm_fourcc.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <sys/mman.h>
@@ skipping 218 matching lines @@
   for (int i = 0; i < resources->count_connectors; ++i) {
     ScopedDrmConnectorPtr connector(
         drmModeGetConnector(fd, resources->connectors[i]));
     connectors.push_back(connector.get());
 
     if (connector && connector->connection == DRM_MODE_CONNECTED &&
         connector->count_modes != 0)
       available_connectors.push_back(std::move(connector));
   }
 
-  base::SmallMap<std::map<ScopedDrmConnectorPtr::element_type*, int>>
+  base::small_map<std::map<ScopedDrmConnectorPtr::element_type*, int>>

[danakj, 2017/04/18 21:35:50]

almost certainly there are few enough monitors that flat_map makes sense. Also
this could build a vector to init the flat_map, as it's walking thru a set of
unique keys.

[brettw, 2017/04/19 16:29:48]

Hopefully someday I can have so many monitors this code becomes slow.

       connector_crtcs;
   for (auto& c : available_connectors) {
     uint32_t possible_crtcs = 0;
     for (int i = 0; i < c->count_encoders; ++i) {
       ScopedDrmEncoderPtr encoder(drmModeGetEncoder(fd, c->encoders[i]));
       if (!encoder)
         continue;
       possible_crtcs |= encoder->possible_crtcs;
     }
     connector_crtcs[c.get()] = possible_crtcs;
@@ skipping 184 matching lines @@
     case gfx::BufferFormat::YUV_420_BIPLANAR:
       return DRM_FORMAT_NV12;
     case gfx::BufferFormat::YVU_420:
       return DRM_FORMAT_YVU420;
     default:
       NOTREACHED();
       return 0;
   }
 }
 }  // namespace ui