Discard tab immediately without waiting for LogMemory().

LogMemory() calls memory::OomMemoryDetails::Log(), which is an async
call and may take a long time (only 60% returns < 1s, 10% returns > 5s).
When we're running out of memory, we need to discard tab faster.

BUG=850545

Change-Id: Ia652b2a80f968b0e437904bb6bc2c7c131c1958d
Reviewed-on: https://chromium-review.googlesource.com/1097038Reviewed-by: Cheng-Yu Lee <cylee@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Commit-Queue: Cheng-Yu Lee <cylee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567891}

chrome/browser/memory/oom_memory_details.cc

@@ -14,16 +14,14 @@
 namespace memory {
 
 // static
-void OomMemoryDetails::Log(const std::string& title,
-                           const base::Closure& callback) {
+void OomMemoryDetails::Log(const std::string& title) {
   // Deletes itself upon completion.
-  OomMemoryDetails* details = new OomMemoryDetails(title, callback);
+  OomMemoryDetails* details = new OomMemoryDetails(title);
   details->StartFetch();
 }
 
-OomMemoryDetails::OomMemoryDetails(const std::string& title,
-                                   const base::Closure& callback)
-    : title_(title), callback_(callback) {
+OomMemoryDetails::OomMemoryDetails(const std::string& title)
+    : title_(title) {
   AddRef();  // Released in OnDetailsAvailable().
   start_time_ = base::TimeTicks::Now();
 }
@@ -45,8 +43,6 @@ void OomMemoryDetails::OnDetailsAvailable() {
 #endif
   LOG(WARNING) << title_ << " (" << delta.InMilliseconds() << " ms):\n"
                << log_string;
-  if (!callback_.is_null())
-    callback_.Run();
   // Delete ourselves so we don't have to worry about OomPriorityManager
   // deleting us when we're still working.
   Release();

chrome/browser/memory/oom_memory_details.h

@@ -7,7 +7,6 @@
 
 #include <string>
 
-#include "base/callback.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "chrome/browser/memory_details.h"
@@ -19,12 +18,12 @@ namespace memory {
 // memory event in an attempt to identify the culprit.
 class OomMemoryDetails : public MemoryDetails {
  public:
-  // Logs the memory details asynchronously and then run |callback|.
+  // Logs the memory details asynchronously.
   // The |title| is printed at the beginning of the message.
-  static void Log(const std::string& title, const base::Closure& callback);
+  static void Log(const std::string& title);
 
  private:
-  OomMemoryDetails(const std::string& title, const base::Closure& callback);
+  OomMemoryDetails(const std::string& title);
   ~OomMemoryDetails() override;
 
   // MemoryDetails overrides:
@@ -32,7 +31,6 @@ class OomMemoryDetails : public MemoryDetails {
 
   std::string title_;
   base::TimeTicks start_time_;
-  base::Closure callback_;
 
   DISALLOW_COPY_AND_ASSIGN(OomMemoryDetails);
 };

chrome/browser/resource_coordinator/tab_manager.cc

@@ -304,14 +304,15 @@ WebContents* TabManager::DiscardTabByExtension(content::WebContents* contents) {
 }
 
 void TabManager::LogMemoryAndDiscardTab(DiscardReason reason) {
-  LogMemory("Tab Discards Memory details",
-            base::Bind(&TabManager::PurgeMemoryAndDiscardTab, reason));
+  // Discard immediately without waiting for LogMemory() (https://crbug/850545).
+  // Consider removing LogMemory() at all if nobody cares about the log.
+  LogMemory("Tab Discards Memory details");
+  PurgeMemoryAndDiscardTab(reason);
 }
 
-void TabManager::LogMemory(const std::string& title,
-                           const base::Closure& callback) {
+void TabManager::LogMemory(const std::string& title) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  memory::OomMemoryDetails::Log(title, callback);
+  memory::OomMemoryDetails::Log(title);
 }
 
 void TabManager::AddObserver(TabLifecycleObserver* observer) {

chrome/browser/resource_coordinator/tab_manager.h

@@ -11,7 +11,6 @@
 #include <string>
 #include <vector>
 
-#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
@@ -119,8 +118,8 @@ class TabManager : public LifecycleUnitObserver,
   // multiple threads and takes time.
   void LogMemoryAndDiscardTab(DiscardReason reason);
 
-  // Log memory statistics for the running processes, then call the callback.
-  void LogMemory(const std::string& title, const base::Closure& callback);
+  // Log memory statistics for the running processes.
+  void LogMemory(const std::string& title);
 
   // TODO(fdoray): Remove these methods. TabManager shouldn't know about tabs.
   // https://crbug.com/775644

chrome/browser/ui/sad_tab.cc

@@ -267,7 +267,7 @@ SadTab::SadTab(content::WebContents* web_contents, SadTabKind kind)
       {
         const std::string spec = web_contents->GetURL().GetOrigin().spec();
         memory::OomMemoryDetails::Log(
-            "Tab OOM-Killed Memory details: " + spec + ", ", base::Closure());
+            "Tab OOM-Killed Memory details: " + spec + ", ");
       }
       FALLTHROUGH;
 #endif