Revert "Android: Adjust tile-size using 'real' resolution in JB-MR1"

Reverting since there is other noise on the perf-bots and I want to be sure this didn't cause it.

This reverts commit 074821be1ec9c73a25e23e6dbcbd8ccd0aec8632.

TBR=zmo@chromium.org
BUG=329439
NOTRY=true

Review URL: https://codereview.chromium.org/134383003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244335 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/gpu/gpu_data_manager_impl_private.cc

@@ -247,45 +247,16 @@ void ApplyAndroidWorkarounds(const gpu::GPUInfo& gpu_info,
   gfx::DeviceDisplayInfo info;
   int default_tile_size = 256;
 
-  // TODO(epenner): Now that this is somewhat generic, maybe we can
-  // unify this for all platforms (http://crbug.com/159524)
-
-  bool real_size_supported = true;
-  int display_width = info.GetPhysicalDisplayWidth();
-  int display_height = info.GetPhysicalDisplayHeight();
-  if (display_width == 0 || display_height == 0) {
-    real_size_supported = false;
-    display_width = info.GetDisplayWidth();
-    display_height = info.GetDisplayHeight();
-  }
-
-  int portrait_width = std::min(display_width, display_height);
-  int landscape_width = std::max(display_width, display_height);
-
-  if (real_size_supported) {
-    // Maximum HD dimensions should be 768x1280
-    // Maximum FHD dimensions should be 1200x1920
-    if (portrait_width > 768 || landscape_width > 1280)
-       default_tile_size = 384;
-    if (portrait_width > 1200 || landscape_width > 1920)
-       default_tile_size = 512;
-
-    // Adjust for some resolutions that barely straddle an extra
-    // tile when in portrait mode. This helps worst case scroll/raster
-    // by not needing a full extra tile for each row.
-    if (default_tile_size == 256 && portrait_width == 768)
-      default_tile_size += 32;
-    if (default_tile_size == 384 && portrait_width == 1200)
-      default_tile_size += 32;
-  } else {
-    // We don't know the exact resolution due to screen controls etc.
-    // So this just estimates the values above using tile counts.
-    int numTiles = (display_width * display_height) / (256 * 256);
-    if (numTiles > 16)
-      default_tile_size = 384;
+  // For very high resolution displays (eg. Nexus 10), set the default
+  // tile size to be 512. This should be removed in favour of a generic
+  // hueristic that works across all platforms and devices, once that
+  // exists: http://crbug.com/159524. This switches to 512 for screens
+  // containing 40 or more 256x256 tiles, such that 1080p devices do
+  // not use 512x512 tiles (eg. 1920x1280 requires 37.5 tiles)
+  int numTiles = (info.GetDisplayWidth() *
+                  info.GetDisplayHeight()) / (256 * 256);
   if (numTiles >= 40)
     default_tile_size = 512;
-  }
 
   // IMG: Fast async texture uploads only work with non-power-of-two,
   // but still multiple-of-eight sizes.