media: Add crash key for CDM version

This makes it much easier to analyse CDM crashes.

Tested with --enable-crash-reporter-for-testing, which will upload
a crash report and print a crash ID to stdout. Then confirmed that
we have the CDM version in the crash report.

See crash ID 27c2f5df78d977e227 for an example crash.

BUG=788937

Change-Id: Ifa565f0d01a78cfef2329704ea3bc3feb9a5723a
Reviewed-on: https://chromium-review.googlesource.com/792258
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521805}

media/cdm/BUILD.gn

@@ -60,6 +60,7 @@ source_set("cdm") {
     deps += [
       ":cdm_api",
       ":cdm_paths",
+      "//components/crash/core/common:crash_key",
     ]
     sources += [
       "cdm_adapter.cc",

media/cdm/DEPS

 include_rules = [
+  "+components/crash/core/common/crash_key.h",
   "+crypto",
   "+ppapi/cpp/logging.h",
 ]

media/cdm/cdm_module.cc

@@ -9,6 +9,7 @@
 #include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "components/crash/core/common/crash_key.h"
 
 #if BUILDFLAG(ENABLE_CDM_HOST_VERIFICATION)
 #include "media/cdm/cdm_host_files.h"
@@ -150,18 +151,27 @@ bool CdmModule::Initialize(const base::FilePath& cdm_path) {
       library_.GetFunctionPointer("DeinitializeCdmModule"));
   create_cdm_func_ = reinterpret_cast<CreateCdmFunc>(
       library_.GetFunctionPointer("CreateCdmInstance"));
+  get_cdm_version_func_ = reinterpret_cast<GetCdmVersionFunc>(
+      library_.GetFunctionPointer("GetCdmVersion"));
 
   if (!initialize_cdm_module_func_ || !deinitialize_cdm_module_func_ ||
-      !create_cdm_func_) {
+      !create_cdm_func_ || !get_cdm_version_func_) {
     LOG(ERROR) << "Missing entry function in CDM at " << cdm_path.value();
     initialize_cdm_module_func_ = nullptr;
     deinitialize_cdm_module_func_ = nullptr;
     create_cdm_func_ = nullptr;
+    get_cdm_version_func_ = nullptr;
     library_.Release();
     ReportLoadResult(LoadResult::kEntryPointMissing);
     return false;
   }
 
+  // In case of crashes, provide CDM version to facilitate investigation.
+  crash_reporter::InitializeCrashKeys();
+  static crash_reporter::CrashKeyString<32> cdm_version_key("cdm-version");
+  std::string cdm_version = get_cdm_version_func_();
+  cdm_version_key.Set(cdm_version);
+
 #if defined(OS_WIN)
   // Load DXVA before sandbox lockdown to give CDM access to Output Protection
   // Manager (OPM).

media/cdm/cdm_module.h

@@ -59,6 +59,7 @@ class MEDIA_EXPORT CdmModule {
  private:
   using InitializeCdmModuleFunc = void (*)();
   using DeinitializeCdmModuleFunc = void (*)();
+  using GetCdmVersionFunc = char* (*)();
 
   CdmModule();
 
@@ -68,6 +69,7 @@ class MEDIA_EXPORT CdmModule {
   CreateCdmFunc create_cdm_func_ = nullptr;
   InitializeCdmModuleFunc initialize_cdm_module_func_ = nullptr;
   DeinitializeCdmModuleFunc deinitialize_cdm_module_func_ = nullptr;
+  GetCdmVersionFunc get_cdm_version_func_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(CdmModule);
 };