Improved word break for BiDi pseudolocalizer.

Characted sequences \n and \t are now treated as word separators
by BiDi pseudolocalizer. This solves issues when text rendering
engine breaks a line in the middle of a text chunk marked with
RLM+RLO and PDF+RLM sequences.

Bug:34064580
Change-Id: I52e6018785fae25479fa167440f24c534b0e3253
Fixes:34064580
Test: make aapt2_tests
Test: Run aapt2_tests binary
diff --git a/tools/aapt/pseudolocalize.cpp b/tools/aapt/pseudolocalize.cpp
index c7fee2c..5c47e0f 100644
--- a/tools/aapt/pseudolocalize.cpp
+++ b/tools/aapt/pseudolocalize.cpp
@@ -360,9 +360,15 @@
     String16 result;
     bool lastspace = true;
     bool space = true;
+    bool escape = false;
+    const char16_t ESCAPE_CHAR = '\\';
     for (size_t i=0; i<source.size(); i++) {
         char16_t c = s[i];
-        space = is_space(c);
+        if (!escape && c == ESCAPE_CHAR) {
+          escape = true;
+          continue;
+        }
+        space = (!escape && is_space(c)) || (escape && (c == 'n' || c == 't'));
         if (lastspace && !space) {
           // Word start
           result += k_rlm + k_rlo;
@@ -371,6 +377,10 @@
           result += k_pdf + k_rlm;
         }
         lastspace = space;
+        if (escape) {
+          result.append(&ESCAPE_CHAR, 1);
+          escape=false;
+        }
         result.append(&c, 1);
     }
     if (!lastspace) {