[LPM] Reduce bound for numbers and disable UBSan on CF.

TBR=mbarbella@chromium.org

Bug: 769578
Change-Id: I2be935a18118c8e1880f3881d1f62e8978bf532b
Reviewed-on: https://chromium-review.googlesource.com/905090Reviewed-by: Jonathan Metzman <metzman@chromium.org>
Reviewed-by: Martin Barbella <mbarbella@chromium.org>
Commit-Queue: Jonathan Metzman <metzman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534739}

testing/libfuzzer/proto/BUILD.gn

@@ -55,9 +55,9 @@ if (!is_win) {
     #  Can't disable instrumentation because of container-overflow false
     # positives.
 
-    # Assertion failures in skia are uninteresting. Don't use debug builds on
-    # CF.
-    if (is_debug) {
+    # Assertion failures and integer oveflows in skia are uninteresting. Don't
+    # use debug builds on CF.
+    if (is_debug || is_ubsan) {
       all_dependent_configs = [ "//testing/libfuzzer:no_clusterfuzz" ]
     }
   }

testing/libfuzzer/proto/skia_image_filter_proto_converter.cc

@@ -195,10 +195,10 @@ const uint8_t Converter::kCountNibBits[] = {0, 1, 1, 2, 1, 2, 2, 3,
                                             1, 2, 2, 3, 2, 3, 3, 4};
 
 // The rest of the Converter attributes are not copied from skia.
-const int Converter::kFlattenableDepthLimit = 4;
+const int Converter::kFlattenableDepthLimit = 3;
 const int Converter::kColorTableBufferLength = 256;
 uint8_t Converter::kColorTableBuffer[kColorTableBufferLength];
-const int Converter::kNumBound = 50;
+const int Converter::kNumBound = 20;
 const uint8_t Converter::kMutateEnumDenominator = 40;
 
 // Does not include SkSumPathEffect, SkComposePathEffect or SkRegion