cros: Log per-process memory use on low memory events

chrome/browser/memory_details.h

Index: chrome/browser/memory_details.h
diff --git a/chrome/browser/memory_details.h b/chrome/browser/memory_details.h
index 568f591328a4af632411c6d058119e1e8db94596..b5edfe498f419ff7ae027953c229b25b6e345309 100644
--- a/chrome/browser/memory_details.h
+++ b/chrome/browser/memory_details.h
@@ -119,13 +119,20 @@ class MemoryDetails : public base::RefCountedThreadSafe<MemoryDetails> {
   // OnDetailsAvailable will be called when this process is complete.
   void StartFetch();
 
-  virtual void OnDetailsAvailable() {}
+  virtual void OnDetailsAvailable() = 0;
+
+  // Returns a string summarizing memory usage of the Chrome browser process
+  // and all sub-processes, suitable for logging.
+  std::string ToLogString();
 
  protected:
   friend class base::RefCountedThreadSafe<MemoryDetails>;
 
   virtual ~MemoryDetails();
 
+  // Updates the global histograms for tracking memory usage.
+  void UpdateHistograms();
+
  private:
   // Collect child process information on the IO thread.  This is needed because
   // information about some child process types (i.e. plugins) can only be taken
@@ -156,10 +163,6 @@ class MemoryDetails : public base::RefCountedThreadSafe<MemoryDetails> {
   // renderer processes is only available there.
   void CollectChildInfoOnUIThread();
 
-  // Each time we take a memory sample, we do a little work to update
-  // the global histograms for tracking memory usage.
-  void UpdateHistograms();
-
   // Returns a pointer to the ProcessData structure for Chrome.
   ProcessData* ChromeBrowser();