Android: lazy initialization for method id.

Rather than requiring early registration for all method id, we can initialize
them lazily as required.
This solves the problem of building against SDK X but running against X - 1.
Also adds a microbenchmark to ensure there are no considerable regressions.
Results are a bit variable, but it hovers over:
[ERROR:jni_android_unittest.cc(125)] JNI LazyMethodIDCall (us) 1983
[ERROR:jni_android_unittest.cc(127)] JNI MethodIDCall (us) 1862

BUG=152987
TEST=JNIAndroidMicrobenchmark.MethodId
TBR=akalin

Review URL: https://chromiumcodereview.appspot.com/11038015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@162186 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 18 insertions, 15 deletions

diff --git a/ui/base/clipboard/clipboard_android.cc b/ui/base/clipboard/clipboard_android.cc
index 19d5752..4d310fb 100644
--- a/ui/base/clipboard/clipboard_android.cc
+++ b/ui/base/clipboard/clipboard_android.cc
@@ -25,7 +25,7 @@ using base::android::ClearException;
 using base::android::ConvertJavaStringToUTF16;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::GetClass;
-using base::android::GetMethodID;
+using base::android::MethodID;
 using base::android::ScopedJavaLocalRef;
 
 namespace ui {
@@ -75,8 +75,9 @@ ClipboardMap::ClipboardMap() {
       GetClass(env, "android/content/Context");
 
   // Get the system service method.
-  jmethodID get_system_service = GetMethodID(env, context_class,
-      "getSystemService",  "(Ljava/lang/String;)Ljava/lang/Object;");
+  jmethodID get_system_service = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, context_class.obj(), "getSystemService",
+      "(Ljava/lang/String;)Ljava/lang/Object;");
 
   // Retrieve the system service.
   ScopedJavaLocalRef<jstring> service_name(env, env->NewStringUTF("clipboard"));
@@ -87,18 +88,18 @@ ClipboardMap::ClipboardMap() {
   // Retain a few methods we'll keep using.
   ScopedJavaLocalRef<jclass> clipboard_class =
       GetClass(env, "android/text/ClipboardManager");
-  set_text_ = GetMethodID(env, clipboard_class,
-                          "setText", "(Ljava/lang/CharSequence;)V");
-  get_text_ = GetMethodID(env, clipboard_class,
-                          "getText", "()Ljava/lang/CharSequence;");
-  has_text_ = GetMethodID(env, clipboard_class,
-                          "hasText", "()Z");
+  set_text_ = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, clipboard_class.obj(), "setText", "(Ljava/lang/CharSequence;)V");
+  get_text_ = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, clipboard_class.obj(), "getText", "()Ljava/lang/CharSequence;");
+  has_text_ = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, clipboard_class.obj(), "hasText", "()Z");
 
   // Will need to call toString as CharSequence is not always a String.
   ScopedJavaLocalRef<jclass> charsequence_class =
       GetClass(env, "java/lang/CharSequence");
-  to_string_ = GetMethodID(env, charsequence_class,
-                           "toString", "()Ljava/lang/String;");
+  to_string_ = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, charsequence_class.obj(), "toString", "()Ljava/lang/String;");
 }
 
 std::string ClipboardMap::Get(const std::string& format) {
diff --git a/ui/base/clipboard/clipboard_unittest.cc b/ui/base/clipboard/clipboard_unittest.cc
index e8b3d39..14a8915 100644
--- a/ui/base/clipboard/clipboard_unittest.cc
+++ b/ui/base/clipboard/clipboard_unittest.cc
@@ -646,6 +646,7 @@ TEST_F(ClipboardTest, InternalClipboardInvalidation) {
   // Simulate that another application copied something in the Clipboard
   //
   std::string new_value("Some text copied by some other app");
+  using base::android::MethodID;
   using base::android::ScopedJavaLocalRef;
 
   JNIEnv* env = base::android::AttachCurrentThread();
@@ -657,8 +658,9 @@ TEST_F(ClipboardTest, InternalClipboardInvalidation) {
   ScopedJavaLocalRef<jclass> context_class =
       base::android::GetClass(env, "android/content/Context");
 
-  jmethodID get_system_service = base::android::GetMethodID(env, context_class,
-      "getSystemService",  "(Ljava/lang/String;)Ljava/lang/Object;");
+  jmethodID get_system_service = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, context_class.obj(), "getSystemService",
+      "(Ljava/lang/String;)Ljava/lang/Object;");
 
   // Retrieve the system service.
   ScopedJavaLocalRef<jstring> service_name(env, env->NewStringUTF("clipboard"));
@@ -669,8 +671,8 @@ TEST_F(ClipboardTest, InternalClipboardInvalidation) {
 
   ScopedJavaLocalRef<jclass> clipboard_class =
       base::android::GetClass(env, "android/text/ClipboardManager");
-  jmethodID set_text = base::android::GetMethodID(env, clipboard_class,
-                          "setText", "(Ljava/lang/CharSequence;)V");
+  jmethodID set_text = MethodID::Get<MethodID::TYPE_INSTANCE>(
+      env, clipboard_class.obj(), "setText", "(Ljava/lang/CharSequence;)V");
 
   // Will need to call toString as CharSequence is not always a String.
   env->CallVoidMethod(clipboard_manager.obj(),