Android: adds Get(Static)MethodIDOrNULL.

When generating JNI bindings for system classes, we try to get the ids
for methods based in the .class file in the SDK.
However, this may trigger run-time errors when trying to run on an older
SDK.
For these system classes, the JNI generator will bind using the "OrNULL"
variation.

BUG=152987
TEST=

Review URL: https://chromiumcodereview.appspot.com/10996063

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@159769 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 79 insertions, 29 deletions

diff --git a/base/android/jni_android.cc b/base/android/jni_android.cc
index d3b4e79..a34bc18 100644
--- a/base/android/jni_android.cc
+++ b/base/android/jni_android.cc
@@ -96,6 +96,36 @@ std::string GetJavaExceptionInfo(JNIEnv* env, jthrowable java_throwable) {
 
   return ConvertJavaStringToUTF8(exception_string);
 }
+
+enum MethodType {
+  METHODTYPE_STATIC,
+  METHODTYPE_NORMAL,
+};
+
+enum ExceptionCheck {
+  EXCEPTIONCHECK_YES,
+  EXCEPTIONCHECK_NO,
+};
+
+template<MethodType method_type, ExceptionCheck exception_check>
+jmethodID GetMethodIDInternal(JNIEnv* env,
+                              jclass clazz,
+                              const char* method_name,
+                              const char* jni_signature) {
+  jmethodID method_id = method_type == METHODTYPE_STATIC ?
+      env->GetStaticMethodID(clazz, method_name, jni_signature) :
+      env->GetMethodID(clazz, method_name, jni_signature);
+  if (exception_check == EXCEPTIONCHECK_YES) {
+    CHECK(!base::android::ClearException(env) && method_id) <<
+      "Failed to find " <<
+      (method_type == METHODTYPE_STATIC ? "static " : "") <<
+      "method " << method_name << " " << jni_signature;
+  } else if (base::android::HasException(env)) {
+    env->ExceptionClear();
+  }
+  return method_id;
+}
+
 }  // namespace
 
 namespace base {
@@ -138,7 +168,7 @@ ScopedJavaLocalRef<jclass> GetClass(JNIEnv* env, const char* class_name) {
 
 jclass GetUnscopedClass(JNIEnv* env, const char* class_name) {
   jclass clazz = env->FindClass(class_name);
-  CHECK(clazz && !ClearException(env)) << "Failed to find class " << class_name;
+  CHECK(!ClearException(env) && clazz) << "Failed to find class " << class_name;
   return clazz;
 }
 
@@ -165,11 +195,16 @@ jmethodID GetMethodID(JNIEnv* env,
                       jclass clazz,
                       const char* method_name,
                       const char* jni_signature) {
-  jmethodID method_id =
-      env->GetMethodID(clazz, method_name, jni_signature);
-  CHECK(method_id && !ClearException(env)) << "Failed to find method " <<
-      method_name << " " << jni_signature;
-  return method_id;
+  return GetMethodIDInternal<METHODTYPE_NORMAL, EXCEPTIONCHECK_YES>(
+      env, clazz, method_name, jni_signature);
+}
+
+jmethodID GetMethodIDOrNull(JNIEnv* env,
+                            jclass clazz,
+                            const char* method_name,
+                            const char* jni_signature) {
+  return GetMethodIDInternal<METHODTYPE_NORMAL, EXCEPTIONCHECK_NO>(
+      env, clazz, method_name, jni_signature);
 }
 
 jmethodID GetStaticMethodID(JNIEnv* env,
@@ -184,11 +219,16 @@ jmethodID GetStaticMethodID(JNIEnv* env,
                             jclass clazz,
                             const char* method_name,
                             const char* jni_signature) {
-  jmethodID method_id =
-      env->GetStaticMethodID(clazz, method_name, jni_signature);
-  CHECK(method_id && !ClearException(env)) << "Failed to find static method " <<
-      method_name << " " << jni_signature;
-  return method_id;
+  return GetMethodIDInternal<METHODTYPE_STATIC, EXCEPTIONCHECK_YES>(
+      env, clazz, method_name, jni_signature);
+}
+
+jmethodID GetStaticMethodIDOrNull(JNIEnv* env,
+                                  jclass clazz,
+                                  const char* method_name,
+                                  const char* jni_signature) {
+  return GetMethodIDInternal<METHODTYPE_STATIC, EXCEPTIONCHECK_NO>(
+      env, clazz, method_name, jni_signature);
 }
 
 bool HasMethod(JNIEnv* env,
@@ -211,10 +251,8 @@ jfieldID GetFieldID(JNIEnv* env,
                     const char* field_name,
                     const char* jni_signature) {
   jfieldID field_id = env->GetFieldID(clazz.obj(), field_name, jni_signature);
-  CHECK(field_id && !ClearException(env)) << "Failed to find field " <<
+  CHECK(!ClearException(env) && field_id) << "Failed to find field " <<
       field_name << " " << jni_signature;
-  bool error = ClearException(env);
-  DCHECK(!error);
   return field_id;
 }
 
@@ -238,10 +276,8 @@ jfieldID GetStaticFieldID(JNIEnv* env,
                           const char* jni_signature) {
   jfieldID field_id =
       env->GetStaticFieldID(clazz.obj(), field_name, jni_signature);
-  CHECK(field_id && !ClearException(env)) << "Failed to find static field " <<
+  CHECK(!ClearException(env) && field_id) << "Failed to find static field " <<
       field_name << " " << jni_signature;
-  bool error = ClearException(env);
-  DCHECK(!error);
   return field_id;
 }
 
diff --git a/base/android/jni_android.h b/base/android/jni_android.h
index 492f11f..40e2359 100644
--- a/base/android/jni_android.h
+++ b/base/android/jni_android.h
@@ -71,6 +71,12 @@ jmethodID GetMethodID(JNIEnv* env,
                       const char* method_name,
                       const char* jni_signature);
 
+// Unlike GetMethodID, returns NULL if the method could not be found.
+jmethodID GetMethodIDOrNull(JNIEnv* env,
+                            jclass clazz,
+                            const char* method_name,
+                            const char* jni_signature);
+
 // Returns the method ID for the static method with the specified name and
 // signature.
 // This method triggers a fatal assertion if the method could not be found.
@@ -86,6 +92,11 @@ jmethodID GetStaticMethodID(JNIEnv* env,
                             const char* method_name,
                             const char* jni_signature);
 
+// Unlike GetStaticMethodID, returns NULL if the method could not be found.
+jmethodID GetStaticMethodIDOrNull(JNIEnv* env,
+                                  jclass clazz,
+                                  const char* method_name,
+                                  const char* jni_signature);
 
 // Returns true iff |clazz| has a method with the specified name and signature.
 bool HasMethod(JNIEnv* env,
diff --git a/base/android/jni_generator/jni_generator.py b/base/android/jni_generator/jni_generator.py
index de3532f..354e33a 100755
--- a/base/android/jni_generator/jni_generator.py
+++ b/base/android/jni_generator/jni_generator.py
@@ -471,7 +471,7 @@ class JNIFromJavaP(object):
       if not match:
         continue
       self.called_by_natives += [CalledByNative(
-          system_class=False,
+          system_class=True,
           unchecked=False,
           static=False,
           java_class_name='',
@@ -923,7 +923,7 @@ jclass g_${JAVA_CLASS}_clazz = NULL;""")
     """Returns the implementation of GetMethodID."""
     template = Template("""\
   g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME} =
-      base::android::Get${STATIC}MethodID(
+      base::android::Get${STATIC}MethodID${SUFFIX}(
           env, g_${JAVA_CLASS}_clazz,
           "${JNI_NAME}",
           ${JNI_SIGNATURE});
@@ -938,6 +938,7 @@ jclass g_${JAVA_CLASS}_clazz = NULL;""")
         'JNI_NAME': jni_name,
         'METHOD_ID_VAR_NAME': called_by_native.method_id_var_name,
         'STATIC': 'Static' if called_by_native.static else '',
+        'SUFFIX': 'OrNull' if called_by_native.system_class else '',
         'JNI_SIGNATURE': JniSignature(called_by_native.params,
                                       jni_return_type,
                                       True)
diff --git a/base/android/jni_generator/jni_generator_tests.py b/base/android/jni_generator/jni_generator_tests.py
index fdedc97..ba9ee21 100755
--- a/base/android/jni_generator/jni_generator_tests.py
+++ b/base/android/jni_generator/jni_generator_tests.py
@@ -1349,6 +1349,8 @@ static jlong Java_InputStream_skip(JNIEnv* env, jobject obj, jlong p0) {
 }
 
 static jmethodID g_InputStream_Constructor = 0;
+static ScopedJavaLocalRef<jobject> Java_InputStream_Constructor(JNIEnv* env)
+__attribute__ ((unused));
 static ScopedJavaLocalRef<jobject> Java_InputStream_Constructor(JNIEnv* env) {
   /* Must call RegisterNativesImpl()  */
   DCHECK(g_InputStream_clazz);
@@ -1365,7 +1367,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
   g_InputStream_clazz = reinterpret_cast<jclass>(env->NewGlobalRef(
       base::android::GetUnscopedClass(env, kInputStreamClassPath)));
   g_InputStream_available =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "available",
 
@@ -1374,7 +1376,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "I");
 
   g_InputStream_close =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "close",
 
@@ -1383,7 +1385,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "V");
 
   g_InputStream_mark =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "mark",
 
@@ -1393,7 +1395,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "V");
 
   g_InputStream_markSupported =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "markSupported",
 
@@ -1402,7 +1404,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "Z");
 
   g_InputStream_readI =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "read",
 
@@ -1411,7 +1413,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "I");
 
   g_InputStream_readI_AB =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "read",
 
@@ -1421,7 +1423,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "I");
 
   g_InputStream_readI_AB_I_I =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "read",
 
@@ -1433,7 +1435,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "I");
 
   g_InputStream_reset =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "reset",
 
@@ -1442,7 +1444,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "V");
 
   g_InputStream_skip =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "skip",
 
@@ -1452,7 +1454,7 @@ static void GetMethodIDsImpl(JNIEnv* env) {
 "J");
 
   g_InputStream_Constructor =
-      base::android::GetMethodID(
+      base::android::GetMethodIDOrNull(
           env, g_InputStream_clazz,
           "<init>",