This patch removes the dependency on libbacktrace from Callstack, as we will not
be using these advanced Android debugging features in Chrome OS.

diff --git a/platform2/aosp/system/core/libutils/CallStack.cpp b/platform2/aosp/system/core/libutils/CallStack.cpp
index fe6f33d..cce3de4 100644
--- a/platform2/aosp/system/core/libutils/CallStack.cpp
+++ b/platform2/aosp/system/core/libutils/CallStack.cpp
@@ -20,8 +20,6 @@
 #include <utils/Errors.h>
 #include <utils/Log.h>
 
-#include <backtrace/Backtrace.h>
-
 #define CALLSTACK_WEAK  // Don't generate weak definitions.
 #include <utils/CallStack.h>
 
@@ -38,16 +36,8 @@ CallStack::CallStack(const char* logtag, int32_t ignoreDepth) {
 CallStack::~CallStack() {
 }
 
-void CallStack::update(int32_t ignoreDepth, pid_t tid) {
+void CallStack::update(int32_t /*ignoreDepth*/, pid_t /*tid*/) {
     mFrameLines.clear();
-
-    std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS, tid));
-    if (!backtrace->Unwind(ignoreDepth)) {
-        ALOGW("%s: Failed to unwind callstack.", __FUNCTION__);
-    }
-    for (size_t i = 0; i < backtrace->NumFrames(); i++) {
-      mFrameLines.push_back(String8(backtrace->FormatFrameData(i).c_str()));
-    }
 }
 
 void CallStack::log(const char* logtag, android_LogPriority priority, const char* prefix) const {
diff --git a/platform2/aosp/system/core/libutils/include/utils/CallStack.h b/platform2/aosp/system/core/libutils/include/utils/CallStack.h
index 7a4a345..fe4d4f5 100644
--- a/platform2/aosp/system/core/libutils/include/utils/CallStack.h
+++ b/platform2/aosp/system/core/libutils/include/utils/CallStack.h
@@ -20,7 +20,6 @@
 #include <memory>
 
 #include <android/log.h>
-#include <backtrace/backtrace_constants.h>
 #include <utils/String8.h>
 #include <utils/Vector.h>
 
@@ -59,7 +58,7 @@ public:
 
     // Immediately collect the stack traces for the specified thread.
     // The default is to dump the stack of the current call.
-    void update(int32_t ignoreDepth = 1, pid_t tid = BACKTRACE_CURRENT_THREAD);
+    void update(int32_t ignoreDepth = 1, pid_t tid = -1);
 
     // Dump a stack trace to the log using the supplied logtag.
     void log(const char* logtag,