UMA: workaround null MemoryInstrumentation

It appears the MemoryInstrumentation singleton can be null in UMA
logging code, possibly because this runs prior to //content
initialization. There's no memory metrics to log in this case, so we
work around this by null-checking the singleton and exiting early.

Fixed: 1140173
Test: None
Change-Id: Id5e783dd068381dac1d7ac48b86764acc54ed620
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533738
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827121}

chrome/browser/metrics/process_memory_metrics_emitter.cc

@@ -649,6 +649,11 @@ void ProcessMemoryMetricsEmitter::FetchAndEmitProcessMemoryMetrics() {
 
   MarkServiceRequestsInProgress();
 
+  auto* instrumentation =
+      memory_instrumentation::MemoryInstrumentation::GetInstance();
+  // nullptr means content layer is not initialized yet (there's no memory
+  // metrics to log in this case)
+  if (instrumentation) {
     // The callback keeps this object alive until the callback is invoked.
     auto callback =
         base::BindOnce(&ProcessMemoryMetricsEmitter::ReceivedMemoryDump, this);
@@ -656,11 +661,11 @@ void ProcessMemoryMetricsEmitter::FetchAndEmitProcessMemoryMetrics() {
     for (const auto& metric : kAllocatorDumpNamesForMetrics)
       mad_list.push_back(metric.dump_name);
     if (pid_scope_ != base::kNullProcessId) {
-    memory_instrumentation::MemoryInstrumentation::GetInstance()
-        ->RequestGlobalDumpForPid(pid_scope_, mad_list, std::move(callback));
+      instrumentation->RequestGlobalDumpForPid(pid_scope_, mad_list,
+                                               std::move(callback));
     } else {
-    memory_instrumentation::MemoryInstrumentation::GetInstance()
-        ->RequestGlobalDump(mad_list, std::move(callback));
+      instrumentation->RequestGlobalDump(mad_list, std::move(callback));
+    }
   }
 
   // Use a lambda adapter to post the results back to this sequence.

components/embedder_support/android/metrics/memory_metrics_logger.cc

@@ -143,9 +143,14 @@ void MemoryMetricsLogger::RecordMemoryMetricsAfterDelay(
 // static
 void MemoryMetricsLogger::RecordMemoryMetrics(scoped_refptr<State> state,
                                               RecordCallback done_callback) {
-  memory_instrumentation::MemoryInstrumentation::GetInstance()
-      ->RequestGlobalDump({}, base::BindOnce(&RecordMemoryMetricsImpl,
-                                             std::move(done_callback)));
+  auto* instrumentation =
+      memory_instrumentation::MemoryInstrumentation::GetInstance();
+  if (!instrumentation) {
+    // Content layer is not initialized yet, nothing to log.
+    return;
+  }
+  instrumentation->RequestGlobalDump(
+      {}, base::BindOnce(&RecordMemoryMetricsImpl, std::move(done_callback)));
   RecordMemoryMetricsAfterDelay(state);
 }