media: Make "clear_key_cdm" target a loadable_module

According to the gn reference (and from brettw@): the "loadable_module"
target type allows you to create an object file that is (and can only
be) loaded and unloaded at runtime, which is exactly what we want for
Clear Key CDM.

Bug: 584449
Test: Existing tests pass.
Change-Id: I2a3a322cb13a7c052c7c43fdd1235ccadd0742ce
Reviewed-on: https://chromium-review.googlesource.com/988814Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547591}

base/native_library.h

@@ -98,13 +98,21 @@ BASE_EXPORT void UnloadNativeLibrary(NativeLibrary library);
 BASE_EXPORT void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                                       StringPiece name);
 
-// Returns the full platform specific name for a native library.
-// |name| must be ASCII.
-// For example:
-// "mylib" returns "mylib.dll" on Windows, "libmylib.so" on Linux,
-// "libmylib.dylib" on Mac.
+// Returns the full platform-specific name for a native library. |name| must be
+// ASCII. This is also the default name for the output of a gn |shared_library|
+// target. See tools/gn/docs/reference.md#shared_library.
+// For example for "mylib", it returns:
+// - "mylib.dll" on Windows
+// - "libmylib.so" on Linux
+// - "libmylib.dylib" on Mac
 BASE_EXPORT std::string GetNativeLibraryName(StringPiece name);
 
+// Returns the full platform-specific name for a gn |loadable_module| target.
+// See tools/gn/docs/reference.md#loadable_module
+// The returned name is the same as GetNativeLibraryName() on all platforms
+// except for Mac where for "mylib" it returns "mylib.so".
+BASE_EXPORT std::string GetLoadableModuleName(StringPiece name);
+
 }  // namespace base
 
 #endif  // BASE_NATIVE_LIBRARY_H_

base/native_library_ios.mm

@@ -14,7 +14,6 @@ std::string NativeLibraryLoadError::ToString() const {
   return message;
 }
 
-// static
 NativeLibrary LoadNativeLibraryWithOptions(const base::FilePath& library_path,
                                            const NativeLibraryOptions& options,
                                            NativeLibraryLoadError* error) {
@@ -24,23 +23,24 @@ NativeLibrary LoadNativeLibraryWithOptions(const base::FilePath& library_path,
   return nullptr;
 }
 
-// static
 void UnloadNativeLibrary(NativeLibrary library) {
   NOTIMPLEMENTED();
   DCHECK(!library);
 }
 
-// static
 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                           StringPiece name) {
   NOTIMPLEMENTED();
   return nullptr;
 }
 
-// static
 std::string GetNativeLibraryName(StringPiece name) {
   DCHECK(IsStringASCII(name));
   return name.as_string();
 }
 
+std::string GetLoadableModuleName(StringPiece name) {
+  return GetNativeLibraryName(name);
+}
+
 }  // namespace base

base/native_library_mac.mm

@@ -38,7 +38,6 @@ std::string NativeLibraryLoadError::ToString() const {
   return message;
 }
 
-// static
 NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
                                            const NativeLibraryOptions& options,
                                            NativeLibraryLoadError* error) {
@@ -75,7 +74,6 @@ NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
   return native_lib;
 }
 
-// static
 void UnloadNativeLibrary(NativeLibrary library) {
   if (library->objc_status == OBJC_NOT_PRESENT) {
     if (library->type == BUNDLE) {
@@ -95,7 +93,6 @@ void UnloadNativeLibrary(NativeLibrary library) {
   delete library;
 }
 
-// static
 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                           StringPiece name) {
   void* function_pointer = nullptr;
@@ -118,10 +115,14 @@ void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
   return function_pointer;
 }
 
-// static
 std::string GetNativeLibraryName(StringPiece name) {
   DCHECK(IsStringASCII(name));
   return "lib" + name.as_string() + ".dylib";
 }
 
+std::string GetLoadableModuleName(StringPiece name) {
+  DCHECK(IsStringASCII(name));
+  return name.as_string() + ".so";
+}
+
 }  // namespace base

base/native_library_posix.cc

@@ -18,7 +18,6 @@ std::string NativeLibraryLoadError::ToString() const {
   return message;
 }
 
-// static
 NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
                                            const NativeLibraryOptions& options,
                                            NativeLibraryLoadError* error) {
@@ -46,7 +45,6 @@ NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
   return dl;
 }
 
-// static
 void UnloadNativeLibrary(NativeLibrary library) {
   int ret = dlclose(library);
   if (ret < 0) {
@@ -55,16 +53,18 @@ void UnloadNativeLibrary(NativeLibrary library) {
   }
 }
 
-// static
 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                           StringPiece name) {
   return dlsym(library, name.data());
 }
 
-// static
 std::string GetNativeLibraryName(StringPiece name) {
   DCHECK(IsStringASCII(name));
   return "lib" + name.as_string() + ".so";
 }
 
+std::string GetLoadableModuleName(StringPiece name) {
+  return GetNativeLibraryName(name);
+}
+
 }  // namespace base

base/native_library_unittest.cc

@@ -40,6 +40,20 @@ TEST(NativeLibraryTest, GetNativeLibraryName) {
   EXPECT_EQ(kExpectedName, GetNativeLibraryName("mylib"));
 }
 
+TEST(NativeLibraryTest, GetLoadableModuleName) {
+  const char kExpectedName[] =
+#if defined(OS_IOS)
+      "mylib";
+#elif defined(OS_MACOSX)
+      "mylib.so";
+#elif defined(OS_POSIX)
+      "libmylib.so";
+#elif defined(OS_WIN)
+      "mylib.dll";
+#endif
+  EXPECT_EQ(kExpectedName, GetLoadableModuleName("mylib"));
+}
+
 // We don't support dynamic loading on iOS, and ASAN will complain about our
 // intentional ODR violation because of |g_native_library_exported_value| being
 // defined globally both here and in the shared library.

base/native_library_win.cc

@@ -150,28 +150,28 @@ std::string NativeLibraryLoadError::ToString() const {
   return StringPrintf("%lu", code);
 }
 
-// static
 NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
                                            const NativeLibraryOptions& options,
                                            NativeLibraryLoadError* error) {
   return LoadNativeLibraryHelper(library_path, error);
 }
 
-// static
 void UnloadNativeLibrary(NativeLibrary library) {
   FreeLibrary(library);
 }
 
-// static
 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
                                           StringPiece name) {
   return reinterpret_cast<void*>(GetProcAddress(library, name.data()));
 }
 
-// static
 std::string GetNativeLibraryName(StringPiece name) {
   DCHECK(IsStringASCII(name));
   return name.as_string() + ".dll";
 }
 
+std::string GetLoadableModuleName(StringPiece name) {
+  return GetNativeLibraryName(name);
+}
+
 }  // namespace base

chrome/browser/load_library_perf_test.cc

@@ -86,7 +86,7 @@ TEST(LoadCDMPerfTest, Widevine) {
 TEST(LoadCDMPerfTest, ExternalClearKey) {
   MeasureSizeAndTimeToLoadCdm(
       media::kClearKeyCdmBaseDirectory,
-      base::GetNativeLibraryName(media::kClearKeyCdmLibraryName));
+      base::GetLoadableModuleName(media::kClearKeyCdmLibraryName));
 }
 
 #endif  // BUILDFLAG(ENABLE_LIBRARY_CDMS)

chrome/browser/media/library_cdm_test_helper.cc

@@ -21,7 +21,7 @@ void RegisterClearKeyCdm(base::CommandLine* command_line,
   cdm_path = cdm_path
                  .Append(media::GetPlatformSpecificDirectory(
                      media::kClearKeyCdmBaseDirectory))
-                 .AppendASCII(base::GetNativeLibraryName(cdm_library_name));
+                 .AppendASCII(base::GetLoadableModuleName(cdm_library_name));
 
   // Append the switch to register the Clear Key CDM path.
   command_line->AppendSwitchNative(switches::kClearKeyCdmPathForTesting,

media/cdm/external_clear_key_test_helper.cc

@@ -37,7 +37,7 @@ void ExternalClearKeyTestHelper::LoadLibrary() {
   cdm_base_path = cdm_base_path.Append(
       GetPlatformSpecificDirectory(kClearKeyCdmBaseDirectory));
   library_path_ = cdm_base_path.AppendASCII(
-      base::GetNativeLibraryName(kClearKeyCdmLibraryName));
+      base::GetLoadableModuleName(kClearKeyCdmLibraryName));
   ASSERT_TRUE(base::PathExists(library_path_)) << library_path_.value();
 
   // Now load the CDM library.

media/cdm/library_cdm/clear_key_cdm/BUILD.gn

@@ -6,7 +6,7 @@ import("//build/config/features.gni")
 import("//media/cdm/library_cdm/cdm_paths.gni")
 import("//media/media_options.gni")
 
-shared_library("clear_key_cdm") {
+loadable_module("clear_key_cdm") {
   output_dir = "$root_out_dir/$clearkey_cdm_path"
   output_name = "clearkeycdm"
   sources = [
@@ -51,10 +51,6 @@ shared_library("clear_key_cdm") {
     defines += [ "CLEAR_KEY_CDM_USE_FFMPEG_DECODER" ]
     deps += [ "//third_party/ffmpeg" ]
   }
-
-  if (is_mac) {
-    ldflags = [ "-Wl,-install_name,@loader_path/libclearkeycdm.dylib" ]
-  }
 }
 
 source_set("clear_key_cdm_proxy") {