[sqlite3] Limit max number of memory pages for fuzzing builds.

R=shess@chromium.org
BUG=675446

Review-Url: https://codereview.chromium.org/2609473004
Cr-Commit-Position: refs/heads/master@{#467984}

third_party/sqlite/BUILD.gn

@@ -137,6 +137,16 @@ if (!use_system_sqlite) {
         "SQLITE_MAX_SQL_LENGTH=128000000",
         "SQLITE_PRINTF_PRECISION_LIMIT=1280000",
       ]
+
+      # During fuzz testing, valid SQL queries generated by fuzzing engine may
+      # lead to large memory allocations. If that happens, fuzzer reports an
+      # out-of-memory error. However, such errors are not valid bugs.
+      # To avoid hitting those irrelevant OOMs, we limit max number of memory
+      # pages, so fuzzer will not crash when reaching the limit.
+      # Apply this for fuzzing builds only, not for all builds with sanitizers.
+      if (use_libfuzzer || use_afl) {
+        defines += [ "SQLITE_MAX_PAGE_COUNT=16384" ]
+      }
     }
 
     include_dirs = [ "amalgamation" ]