Fix clang-tidy performance-faster-string-find warnings

Bug: 30411878
Test: build with WITH_TIDY=1
Change-Id: I7fd815aa401fbcaff97b772f3ba5d6f1d2034011

startop/view_compiler/dex_layout_compiler.cc

@@ -118,7 +118,7 @@ namespace {
 std::string ResolveName(const std::string& name) {
   if (name == "View") return "android.view.View";
   if (name == "ViewGroup") return "android.view.ViewGroup";
-  if (name.find(".") == std::string::npos) {
+  if (name.find('.') == std::string::npos) {
     return StringPrintf("android.widget.%s", name.c_str());
   }
   return name;
@@ -205,4 +205,4 @@ void DexViewBuilder::PopViewStack() {
   view_stack_.pop_back();
 }
 
-}  // namespace startop
+}  // namespace startop

startop/view_compiler/util.cc

@@ -23,13 +23,13 @@ namespace util {
 
 // TODO: see if we can borrow this from somewhere else, like aapt2.
 string FindLayoutNameFromFilename(const string& filename) {
-  size_t start = filename.rfind("/");
+  size_t start = filename.rfind('/');
   if (start == string::npos) {
     start = 0;
   } else {
     start++;  // advance past '/' character
   }
-  size_t end = filename.find(".", start);
+  size_t end = filename.find('.', start);
 
   return filename.substr(start, end - start);
 }

tools/aapt2/dump/DumpManifest.cpp

@@ -1175,7 +1175,7 @@ class Activity : public ManifestExtractor::Element {
     }
 
     // Fully qualify the activity name
-    ssize_t idx = name.find(".");
+    ssize_t idx = name.find('.');
     if (idx == 0) {
       name = package + name;
     } else if (idx < 0) {
@@ -2125,7 +2125,7 @@ bool ManifestExtractor::Dump(text::Printer* printer, IDiagnostics* diag) {
     size_t pos = file_path.find("lib/");
     if (pos != std::string::npos) {
       file_path = file_path.substr(pos + 4);
-      pos = file_path.find("/");
+      pos = file_path.find('/');
       if (pos != std::string::npos) {
         file_path = file_path.substr(0, pos);
       }

tools/aapt2/java/ManifestClassGenerator.cpp

@@ -39,7 +39,7 @@ static Maybe<std::string> ExtractJavaIdentifier(IDiagnostics* diag, const Source
   }
 
   // Normalize only the java identifier, leave the original value unchanged.
-  if (result.find("-") != std::string::npos) {
+  if (result.find('-') != std::string::npos) {
     result = JavaClassGenerator::TransformToFieldName(result);
   }